The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
Co-channel and adjacent-channel interference evaluation of an outdoor telecom...Konstantinos Stamatakis
The objective of the present paper is to evaluate the
impact of adjacent and co-channel interference on the
performance of some standard report systems that exists in an
outdoor telecommunications cabinet - base station (BS) (also
known as KV, from the acronym of the German word
Kabelverzweiger) and devices that technicians frequently use.
Specifically, the interference analyzed is between devices, such as
Bluetooth handset, laptop and measurement tools, that are
usually used during inspections and repairs by technicians and
wireless reporting systems installed inside BS that provide
information about BS’s condition and real time connection with
the help desk back office
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
Overview of handover decision strategies in heterogeneous networks by narendr...Narendra Prajapati
The availability of diverse wireless access technologies such as (Wi-Fi), (WiMAX), and (UMTS) allows users to stay “always on” in fast roaming too using IEEE802.21.
Vertical handovers had made possible for user to transfer itself to other technology service without disturbances in ongoing process.
Its is known that security problems in GSM authentication when it comes to high speed moving users, because of there frequent change of cell sites.
Handover could be horizontal or vertical and per user requirement. MIH (media independent handover) though provide vertical handover but on other hand 802.11had provided us fast and secure connection oriented handover from one access point to another with in same mobility domain.
Thus feature of security and authentication is integrated with handover for user security.
What are heterogeneous networks?
Evolutions of Generations
The Cellular GSM Transitions
Overview of 4G Communications
Concept of Handover /Handoff
Handovers distinguished according to criteria
The Vertical handover IEEE 802.21 & its phases.
VHO Management procedures
Requirements of Handover mechanism in heterogeneous networks
Performance evaluation (Technology )
Performance evaluation in Handover mechanisms
Co-channel and adjacent-channel interference evaluation of an outdoor telecom...Konstantinos Stamatakis
The objective of the present paper is to evaluate the
impact of adjacent and co-channel interference on the
performance of some standard report systems that exists in an
outdoor telecommunications cabinet - base station (BS) (also
known as KV, from the acronym of the German word
Kabelverzweiger) and devices that technicians frequently use.
Specifically, the interference analyzed is between devices, such as
Bluetooth handset, laptop and measurement tools, that are
usually used during inspections and repairs by technicians and
wireless reporting systems installed inside BS that provide
information about BS’s condition and real time connection with
the help desk back office
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
Overview of handover decision strategies in heterogeneous networks by narendr...Narendra Prajapati
The availability of diverse wireless access technologies such as (Wi-Fi), (WiMAX), and (UMTS) allows users to stay “always on” in fast roaming too using IEEE802.21.
Vertical handovers had made possible for user to transfer itself to other technology service without disturbances in ongoing process.
Its is known that security problems in GSM authentication when it comes to high speed moving users, because of there frequent change of cell sites.
Handover could be horizontal or vertical and per user requirement. MIH (media independent handover) though provide vertical handover but on other hand 802.11had provided us fast and secure connection oriented handover from one access point to another with in same mobility domain.
Thus feature of security and authentication is integrated with handover for user security.
What are heterogeneous networks?
Evolutions of Generations
The Cellular GSM Transitions
Overview of 4G Communications
Concept of Handover /Handoff
Handovers distinguished according to criteria
The Vertical handover IEEE 802.21 & its phases.
VHO Management procedures
Requirements of Handover mechanism in heterogeneous networks
Performance evaluation (Technology )
Performance evaluation in Handover mechanisms
UNIT I
WIRELESS COMMUNICATION
Cellular systems- Frequency Management and Channel Assignment- types of handoff and their characteristics, dropped call rates & their evaluation -MAC – SDMA – FDMA –TDMA – CDMA – Cellular Wireless Networks
Device-to-device (D2D) communications underlaying a cellular infrastructure has been proposed as a means of taking advantage of the physical proximity of communicating devices, increasing resource utilization, and improving cellular coverage. Relative to the traditional cellular methods, there is a need to design new peer discovery methods, physical layer procedures, and radio resource management algorithms that help realize the potential article we use the 3GPP Long Term Evolution system as a baseline for D2D design, review some of the key design challenges, and propose solution approaches that allow cellular devices and D2D pairs to share spectrum resources and thereby increase the spectrum and energy efficiency of traditional cellular networks. Sim- ulation results illustrate the viability of the proposed design.
International Journal of Computational Engineering Research(IJCER) ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Evaluation of Percentage Capacity Loss on LTE Network Caused by Intermodulati...Onyebuchi nosiri
Abstract- The paper evaluates the effects of third order Intermodulation Distortion (IMD3) on the Long Term Evolution (LTE) receiver due to coexistence between LTE and GSM networks. Amongst the various existing IMD orders which include first order, second order, third order, fifth order and seventh order. Third order is known to have the greatest distortion effects on a receiver due to its strength and its proximity to the frequency band of interest. It occurs as a result of the non-linear behavior of components or circuit at both the transmitter and receiver ends of wireless communication networks. IMD has potential negative effects on a victim receiver which majorly leads to increase in noise floor level and system capacity degradation. Deterministic approach was implemented in the work assuming worst case scenario. MATLAB software simulation was deployed to evaluate the capacity loss at the receiver end relative to a range of distances apart. Results obtained showed severe uplink capacity degradation when VISAFONE LTE network was interfered by INTERCELLULAR LTE downlink and ETISALAT GSM uplink. Various distances ranging from 500m to 3000m were varied between the ETISALAT GSM network and the VISAFONE LTE network. The results obtained showed that at 500 meters, the percentage capacity degradation was as high as 80. The least percentage capacity loss was obtained as 5.97 at 3000 meters.
IMPLEMENTATION OF LINEAR DETECTION TECHNIQUES TO OVERCOME CHANNEL EFFECTS IN ...IJCI JOURNAL
Spatial diversity technique enables improvement in quality and reliability of wireless link. Antenna
diversity along with understanding effects of channel on transmitted signal and methods to overcome the
channel impairment plays an important role in wireless communication where sharing of channel occurs
between users. In this paper single input single output system (SISO) is compared with multiple input
multiple output system (MIMO) in terms of bit error rate performance. Bit error rate performance is also
evaluated for MIMO with least squares (LS) and Minimum mean square error (MMSE) linear detection.
Further analysis and simulation is done to understand the effect of channel imperfections on BER.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
UNIT I
WIRELESS COMMUNICATION
Cellular systems- Frequency Management and Channel Assignment- types of handoff and their characteristics, dropped call rates & their evaluation -MAC – SDMA – FDMA –TDMA – CDMA – Cellular Wireless Networks
Device-to-device (D2D) communications underlaying a cellular infrastructure has been proposed as a means of taking advantage of the physical proximity of communicating devices, increasing resource utilization, and improving cellular coverage. Relative to the traditional cellular methods, there is a need to design new peer discovery methods, physical layer procedures, and radio resource management algorithms that help realize the potential article we use the 3GPP Long Term Evolution system as a baseline for D2D design, review some of the key design challenges, and propose solution approaches that allow cellular devices and D2D pairs to share spectrum resources and thereby increase the spectrum and energy efficiency of traditional cellular networks. Sim- ulation results illustrate the viability of the proposed design.
International Journal of Computational Engineering Research(IJCER) ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Evaluation of Percentage Capacity Loss on LTE Network Caused by Intermodulati...Onyebuchi nosiri
Abstract- The paper evaluates the effects of third order Intermodulation Distortion (IMD3) on the Long Term Evolution (LTE) receiver due to coexistence between LTE and GSM networks. Amongst the various existing IMD orders which include first order, second order, third order, fifth order and seventh order. Third order is known to have the greatest distortion effects on a receiver due to its strength and its proximity to the frequency band of interest. It occurs as a result of the non-linear behavior of components or circuit at both the transmitter and receiver ends of wireless communication networks. IMD has potential negative effects on a victim receiver which majorly leads to increase in noise floor level and system capacity degradation. Deterministic approach was implemented in the work assuming worst case scenario. MATLAB software simulation was deployed to evaluate the capacity loss at the receiver end relative to a range of distances apart. Results obtained showed severe uplink capacity degradation when VISAFONE LTE network was interfered by INTERCELLULAR LTE downlink and ETISALAT GSM uplink. Various distances ranging from 500m to 3000m were varied between the ETISALAT GSM network and the VISAFONE LTE network. The results obtained showed that at 500 meters, the percentage capacity degradation was as high as 80. The least percentage capacity loss was obtained as 5.97 at 3000 meters.
IMPLEMENTATION OF LINEAR DETECTION TECHNIQUES TO OVERCOME CHANNEL EFFECTS IN ...IJCI JOURNAL
Spatial diversity technique enables improvement in quality and reliability of wireless link. Antenna
diversity along with understanding effects of channel on transmitted signal and methods to overcome the
channel impairment plays an important role in wireless communication where sharing of channel occurs
between users. In this paper single input single output system (SISO) is compared with multiple input
multiple output system (MIMO) in terms of bit error rate performance. Bit error rate performance is also
evaluated for MIMO with least squares (LS) and Minimum mean square error (MMSE) linear detection.
Further analysis and simulation is done to understand the effect of channel imperfections on BER.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Multicarrier modulation can be implemented by using Orthogonal Frequency Division Multiplexing (OFDM) to achieve utmost bandwidth exploitation and soaring alleviation attributes profile besides multipath fading. To support delay sensitive and band bandwidth demanding multimedia applications and internet services, MIMO in addition with other techniques can be used to achieve high capacity and reliability. To obtain high spatial rate by transmitting data on several antennas by using MIMO with OFDM results in reducing error recovery features and the equalization complexities arise by sending data on varying frequency levels. Three parameters frequency OFDM, Spatial (MIMO) and time (STC) can be used to achieve diversity in MIMO-OFDM. This technique is dynamic and well-known for services of wireless broadband access. MIMO if used with OFDM is highly beneficial for each scheme and provides high throughput. There are several space time block codes to exploit MIMO OFDM; one of the techniques is called Alamouti Codes. The paper investigates adaptive Alamouti Codes and their application in IEEE 802.11n.
Successful interference cancellation with Blind Equalization method for MC-CD...IJTET Journal
Abstract— The increasing demand for wireless services has created the need for cost effective transmission techniques that can exploit scarce spectral resources efficiently. Inorder to achieve the high data rates needed to meet the quality of service requirements of future multimedia applications, MC-CDMA has been considered as good air-interface candidate, especially for the downlink. However, the user capacity of MC-CDMA system is essentially limited by interference. This interference can be mitigated by employing precoding techniques, IB-DFE based receivers and other efficient interference suppression techniques. In the proposed system, combined Iterative IA precoding at the transmitter with IB-DFE based processing at the receiver is suggested for MC-CDMA systems. The matrices for this nonlinear space-frequency equalizer are obtained by minimizing the overall MSE of all data streams at each subcarrier.
CDMA Transmitter and Receiver Implementation Using FPGAIOSR Journals
Abstract: Code Division Multiple Access (CDMA) is a spread spectrum technique that uses neither frequency channels nor time slots. With CDMA, the narrow band message (typically digitized voice data) is multiplied by a large bandwidth signal that is a pseudo random noise code (PN code). All users in a CDMA system use the same frequency band and transmit simultaneously. The transmitted signal is recovered by correlating the received signal with the PN code used by the transmitter. The DS - CDMA is expected to be the major medium access technology in the future mobile systems owing to its potential capacity enhancement and the robustness against noise. The CDMA is uniquely featured by its spectrum-spreading randomization process employing a pseudo-noise (PN) sequence, thus is often called the spread spectrum multiple access (SSMA). As different CDMA users take different PN sequences, each CDMA receiver can discriminate and detect its own signal, by regarding the signals transmitted by other users as noise- like interferences. In this project direct sequence principle based CDMA transmitter and receiver is implemented in VHDL for FPGA. Modelsim 6.2(MXE) tool will be used for functional and logic verification at each block. The Xilinx synthesis technology (XST) of Xilinx ISE 9.2i tool will be used for synthesis of transmitter and receiver on FPGA Spartan 3E. Keywords: CDMA, DSSS, BPSK, GOLD code.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A Review on Cooperative Communication Protocols in Wireless World ijwmn
Future generations of cellular communications requires higher data rates and a more reliable
transmission link with the growth of multimedia services, while keeping satisfactory quality of service, .
MIMO antenna systems have been considered as an efficient approach to address these demands by
offering significant multiplexing and diversity gains over single antenna systems without increasing
bandwidth and power. Although MIMO systems can unfold their huge benefit in cellular base stations,
but they may face limitations when it comes to their deployment in mobile handsets.
To overcome this drawback, relays (fixed or mobile terminals) can cooperate to improve the overall
system performance in cellular networks. Cooperative communications can efficiently combat the severity
of fading and shadowing through the assistance of relays. It has been found that using relays the capacity
and coverage of cellular networks can be extended without increasing mobile transmit power or
demanding extra bandwidth.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Analysis of Multi-QoS Model of OCDMA System by Adopting OPPM Sign...IJERA Editor
In this paper, optical CDMA which combines the large bandwidth of the fibre medium with the flexibility of the
CDMA technique to achieve high speed connectivity has been used. For achieving this purpose, OPPM
signalling and switching techniques have been employed. This helps in the achievement of high tolerance to
Multiple Access Interference, further resulting in improvement of both the Bit Error Rate and optical channel
capacity without the need to decrease the light pulse width. An OPPM scheme to support multimedia services
with different transmission rates and Quality of Service requirements is proposed. Packet Switching technique
has been employed to help in the transfer of data in the form of packets from the source to the destination via a
specified route. The results are calculated by using PPM signalling and switching technology.But switching
technology has been found to be far better than the OOK-OCDMA if the average power has been considered as
the restraining factor.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Comparative Analysis of Maximum Ratio Combining and Equal Gain Combining Diversity Technique for WCDMA: A Survey
1. International Journal of Engineering Inventions
e-ISSN: 2278-7461, p-ISSN: 2319-6491
Volume 3, Issue1 (August 2013) PP: 72-77
www.ijeijournal.com P a g e | 72
Comparative Analysis of Maximum Ratio Combining and Equal
Gain Combining Diversity Technique for WCDMA: A Survey
Sarita Rohilla1
Dipesh Kumar Patidar2
Naresh Kumar Soni3
1,2,3
Department of Electronics
1
JNU Jaipur, 2
Poornima Institute of Engg. & Tech. , 3
JNU Jaipur
ABSTRACT: Wide Code Division Multiple Access (WCDMA) is a third generation wireless communication
system. However for any wireless communication system there are various factors such as fading, interference
and scattering that degrade the performance of the system. Diversity is an influential communication technique
that provides wireless link enhancement at a relatively low cost. It has been used to mitigate the fading problem
in wireless channel. This survey provides overview of different diversity techniques to overcome the effect of
fading .The Maximum Ratio Combining (MRC) is one of the combining technique used to improve the
performance of wireless communication system. In WCDMA, each user is assigned a unique code that identifies
the user to the system and this code is used to modulate and demodulate the user’s data. In many diversity
techniques space diversity technique is very effective due to its simplicity and bandwidth efficiency. It can be
implemented at both the transmitting and the receiving end. The Maximum Ratio Combining performance is the
best compare to Equal Gain Combining and Selection Combining in Rayleigh fading channel. For the same
SNRs signals to both branches, the output of maximal ratio combiner is more than equal gain combiner. This is
due to ability of updating the weight coefficient in Maximal Ratio combining technique.
Keywords: Fading, Multi Path Propagation, Diversity Technique, Maximum Ratio Combining (MRC), Equal
Gain Combining (EGC), Selection Combining (SC).
I. INTRODUCTION
1.1 History of WCDMA
Bell laboratories developed the cellular concept in the 1960s and AT&T proposed the concept of
cellular mobile system to the Federal Communication Commission (FCC) in 1968s. The first cellular system
was Advance Mobile Phone System (AMPS). The AMPS allocated 60 KHz of bandwidth to each voice user in
each cell and this allocation consisted of two 30KHz Channels: One for the uplink and other for downlink [1].
The AMPS phones were two way FM radios and share spectrum amongst users and this technology become
Frequency Division Multiple Access (FDMA). The first digital cellular phone standard IS-54 supported three
users in each 30 KHz of bandwidth used in AMPS system [2]. Wireless communication technologies have
developed very rapidly in the recent years to improve the performance of the system. In CDMA, a signal was
multiplied by a pseudo-noise code sequence with a higher rate than the data rate of message. The resultant signal
appeared as random and the process was reversed at receiver and the original signal was extracted. Use of
unique code lead to repetition of the same frequency in all cells. However, each user transmitted all of the time
over all of the frequency but used one of ten available orthogonal codes to ensure that there was no interference
with the other nine using orthogonal code [3]. In CDMA, a single 1.25 MHz radio channel carries 64
simultaneous voice channels [4]. The CDMA has two types non-orthogonal and orthogonal. Generated by
pseudo-noise was called non-orthogonal CDMA. In orthogonal CDMA, all users are perfectly uncorrelated to
one other and aligned in time to retain their orthogonality. The narrowband message signal is multiplied by a
very large bandwidth signal called the spreading signal. In spread spectrum technique each users is multiplied
with pseudo-noise code sequence and increase the bandwidth of users . The 3rd Generation Partnership Project
(3GPP) and 3rd Generation Partnership Project two (3GPP2) had developed Wideband Code Division Multiple
Access (WCDMA) technology. Now the WCDMA technology is used in third generation wireless system to
achieve data transmission at variable rate with different mobility and quality of services (QoS) standard cell for
increasing the transmission rate from the 14.4 kb/s voice rate currently support up to 384 kb/s for mobile users
and 2 Mb/s for portable terminals. WCDMA is the second 3Gair interface standard based on CDMA. WCDMA
is an asynchronous scheme and uses a 5MHz carrier frequency. The use of a wider carrier aims to provide
support for high data rates. However using wider carriers requires more available spectrum. WCDMA is
considered to be wideband technologies based on the direct sequence spread spectrum transmission scheme,
where user information bits are spread over a wide bandwidth by multiplying the user data with quasi-random
bits called chips derived from CDMA spreading codes. In order to support very high bit rates (up to 2 Mbps),
2. Comparative Analysis of Maximum Ratio Combining and Equal Gain Combining Diversity
Technique for WCDMA: A Survey
www.ijeijournal.com P a g e | 73
the use of a variable spreading factor is supported. The chip rate 3.84 Mcps leads a carrier bandwidth of 5MHz
[5, 6]. The key operational features of the WCDMA radio interface are:
1. Supported of high data rate transmission: 384 kbps with wide area coverage, 2Mbps with local
coverage.
2. Providing high service flexibility is supporting multiple parallel variable rate services on each
connection.
3. Supported both Frequency Division Duplex (FDD) and Time Division Duplex (TDD).
4. Built in support for future capacity and coverage enhancing technologies such as adaptive antennas,
advanced receiver structures and transmitter diversity.
5. Efficient packet access.
1.2 Problems Associated With Wireless Communication
When a signal is transmitted from source to destination through the channel, There are two main
aspects related to performance of wireless communication, first is the phenomenon of fading: the time-variation
of the channel strengths due to the small-scale effect of multipath fading, as well as larger scale effects such as
path loss via distance attenuation and shadowing by obstacles and second is unlike in the wired world where
each transmitter-receiver pair can often be thought of as an isolated point-to-point link, the wireless users
communicate over the air and there is significant interference between them in wireless communication. One of
the most powerful techniques to mitigate the effects of fading is to use diversity combining of independently
fading signal paths. Other aspects that may also affect the performance of wireless communication are Path loss
and Noise [8].
1.2.1 Fading
In wireless communications, fading is deviation of the attenuation affecting a signal over certain
propagation media. The fading may vary with time, geographical position or radio frequency, and is often
modeled as a random process. The time variation of received signal power caused by changes in the
transmission medium leads to Fading. In a fixed environment, received signal is affected by changes in
atmospheric conditions, such as rainfall [4]. In wireless systems, fading may either be due to multipath
propagation, referred to as multipath induced fading or due to shadowing from obstacles affecting the wave
propagation, sometimes referred to as shadow fading. In a wireless mobile system a signal can travel from
transmitter to receiver through multiple reflective paths which is known as multipath propagation. Multipath
propagation causes fluctuations in signal’s amplitude, phase and angle of arrival creating multipath fading.
There are basically three propagation mechanisms playing a role in the multipath fading, viz. reflection,
diffraction, scattering.
(a) Reflections occur when a propagating electromagnetic signal encounters a smooth surface which is large
relative to the signal’s wavelength. This usually happens when the signal enters a building and the reflection
may occur at the wall of the building.
(b) Diffraction occurs at the edge of a dense body which is larger compared to the signal’s wavelength.
Diffractions will result in the bending of the signal making it possible for the receiver to receive the signal even
when there no direct path between the transmitter and receiver. It usually occurs on irregular surfaces such as
sharp edges.
(c)Scattering usually occurs when the signal is subjected to a large number of objects smaller than the signals
wavelength thus causes the incoming signal to spread out (scatter) into several weaker outgoings in all
directions. This happens usually when the signal passes through a medium containing vegetations, forest, clouds
and etc.
1.2.2 Interference
Interference is the major limiting factor in the performance of cellular system. Source of interference
include another mobile in the same cell. Interference on voice channel cause cross talk. On control channel,
interference leads to missed and blocked calls to errors in the digital signaling. The two major types of system-
generated cellular interference are co-channel interference and adjacent channel interference. Co-channel
interference (intra-cell) is due to the signal from the other users in the home cell. Co-channel interference is
estimated by Carrier-to-interference ratio.
1.2.3 Noise
Noise in wireless communication systems is any unwanted fluctuation, instability or disruption that
induces itself within the transmitted data signal via different mediums and interfering objects. This abrupt
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fluctuation is also a basic characteristic of data signals, which are modulated electromagnetic waves that travel
through the air from electronic communication devices and circuits [8].
(a)Thermal noise is produced from random electron motion and is characterized by a uniform distribution of
energy over the frequency spectrum with a Gaussian distribution. Every electronic equipment or transmission
medium contributes thermal noise to a communication system as long as the temperature of that device or
medium is above absolute zero. Thus it cannot be eliminated.
(b)Impulse noise is a non-continuous series of irregular pulses or noise "spikes" of short duration, broad spectral
density and of relatively high amplitude. It is usually caused by communication.
(c)White noise is a random signal with a flat power spectral density which means that the signal contains equal
power within a fixed bandwidth at any centre frequency. White noise draws its name from white light in which
the power spectral density of the light is distributed over the visible band in such a way that the eye's three color
receptors are approximately equally stimulated. A random signal is considered "white noise" if it is observed to
have a flat spectrum over a medium's widest possible bandwidth.
II. OVERVIEW OF DIVERSITY TECHNIQUES
In wireless applications, due to multipath propagation fading strictly impacts the system performance.
Diversity is the technique which is used in wireless communications systems to improve the performance over a
fading radio channel. Diversity techniques has a significant role to play in wireless communications systems for
a host of applications such as digital cellular networks, mobile radio, wireless LAN’s, wireless local loops,
digital audio, television broadcasting systems, indoor wireless and personal communication systems [9].The
effects of fading can be moderate during the use of diversity techniques in such systems via accurately designed
signal processing algorithms at both the transmitters and receivers. The basic concept of diversity is that if one
signal path undergoes a deep fade at a particular point of time, another independent path may have a strong
signal. Here receiver is provided with multiple copies of the same information signal which are transmitted over
two or more real or virtual communication channels. Thus it can be considered as the diversity is the repetition
or redundancy of information. Mainly the diversity decisions are made by the receiver and are unknown to the
transmitter [10]. Diversity techniques are based on different structures where receiver gets several signals
bearing the same information, through independently fading channels.
III. DIVERSITY TECHNIQUES
The various kinds of diversity techniques, used for wireless communication systems, are discussed here in this
section:
3.1 Frequency Diversity
In this technique the same information signal is transmitted on multiple frequency slots and the
frequency separation between them being at least the coherence bandwidth ∆fc of the channel as shown in Fig. 1.
In practice, frequency diversity is usually achieved by using spread spectrum signals, i.e. direct sequence,
frequency hopping or multicarrier spread spectrum modulation.
f
fc
t
Fig. 1: Frequency diversity [10]
Spread Spectrum Modulation and Orthogonal Frequency Division Multiplexing (OFDM) are
considered as frequency diversity techniques. OFDM exploits frequency diversity by providing simultaneous
modulation signals with error control coding across a large bandwidth, so that if a particular frequency
undergoes a fade, the composite signal will still be demodulated [3]. Spread spectrum techniques are ineffective
S (t)
S (t)
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when the coherence bandwidth of the channel is larger than the spreading bandwidth or equivalently. To reduce
the effects of time delay spread, frequency hopping or direct sequence spread-spectrum modulation can be used.
Frequency diversity is accompanied by the additional cost of increased complexity at both the transmitter and
receiver, along with the fact that it may be difficult to implement in bandwidth-limited systems.
3.2 Time Diversity
In time diversity, the same information signal is transmitted in different time slots. The separation
between the time slots has to be at least the coherence time ∆tc as shown in Fig. 2. The time interval depends on
the fading rate and increases with the decrease in the rate of fading [3]. A coding structure such as interleaving
is often used to realize time diversity where the receiver knows the code before any transmission takes place.
Time interleaving, together with error correction coding can provide diversity improvement [7].
f
∆ tc
t
Fig. 2: Time diversity [10]
If the channel is time varying, each copy will experience different channel conditions and by which
there will be multiple, independently faded copies of the transmitted signal at the receiver. Time diversity
technique is usually effective for fast fading environment where the coherence time of the channel is small .For
slow fading channel, a very large time delay is required, which may create significant problems for delay
sensitive applications such as voice transmission.
3.3 Space Diversity
Space diversity also known as antenna diversity and it uses two or more antenna to improve the quality
and reliability of a wireless link. Space diversity especially used in urban and indoor environment, because there
is not a clear line of sight (LOS) between transmitter and receiver. The signal which may be reflected along the
multiple paths is designed with phase shift, time delay and got attenuated. The space diversity scheme is much
effective for mitigating these multipath situations because multiple antennas at the receiver can afford several
observation of the same signal. So in most scattering environments, antenna diversity is a practical, effective and
widely used technique for reducing the effect of multipath fading. When multiple antennas are used at the
receiver, the scheme becomes receive diversity and for transmit diversity, multiple antennas are used at the
transmitter as shown in Fig. 3 and Fig. 4.
Fig. 3: Receive diversity [10]
S (t) S (t)
Transmitter
Receiver
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Fig. 4: Transmit diversity [10]
3.4 Polarization Diversity
In recent times, polarization diversity is used to mitigate multipath fading. At the base station, this
reduces the size of the antenna. e space diversity technique is often used in the base station but this technique
requires two horizontally separated antennas per sector. Polarization diversity technique contains a dual
polarized antenna, in which only one antenna per sector is required. In space diversity, the diversity antennas to
be spaced apart, whereas the polarization diversity technique uses all antennas with coincident phase centers.
Signals transmitted in either horizontal or vertical electric fields are uncorrelated at both the mobile and base
station receivers. The horizontal and vertical polarization components, Ex and Ey, transmitted by two polarized
antennas at the base station and received by two polarized antennas at the mobile unit, can provide two
uncorrelated fading signals. The decorrelation for the signals in each polarization is caused by multiple
reflections in the channel between the mobile and base station. After sufficient random reflections, the
polarization state of the signal will be independent of the transmitted polarization. In this technology the electric
and magnetic fields of the signal carrying the information are modified and number of such signals are used to
send the same information and thus orthogonal type of polarization is obtained.
IV. DIVERSITY COMBINING METHODS
A classification of diversity schemes can be made based on combining methods. In order to get the
diversity gain, the signals from multiple channels have to be combined, and the combining method affects the
performance of the diversity technique. The diversity combining methods increases the overall received power.
These methods are used to combine several copies of the transmitted signal, which undergo independent fading.
The three types of diversity combining methods are discussed here.
4.1 Selection Combining (SC)
In selection combining scheme, the branch that receives the signal with the largest signal-to-noise ratio
is selected at any time from a collection of antennas and connected to the demodulator. The receiver monitors
the signal-to-noise ratio of both channels and connects the branch with largest SNR to the demodulator at any
instant in time. In order to prevent phase discontinuities when the receiver switches between both branches,
which occurs when one signal falls below the other and receiver switches to the strongest branch, the signals in
both channels are constantly co-phased.
4.2 Maximum Ratio Combining (MRC)
In maximum ratio combining, all the branches are used simultaneously. Each of the branch signals is
weighted with a gain factor which is proportional to its own SNR. Then co-phasing and summing is done for
adding up the weighted branch signals in phase. The Fig.1.8 shows the configuration for a two-branch diversity
system. The both branches are weighted by their respective signal-to-noise ratios. The branches are then co-
phased prior to summing in order to insure that all branches are added in phase for maximum diversity gain. The
summed signals are then used as the received signal and connected to the demodulator.
4.3 Equal Gain Combining (EGC)
In Equal gain combining (EGC), the outputs of different diversity branches are first co-phased and
weighted equally before being summed to give the resultant output. After that the resultant output signal is
Transmitter
Receiver
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connected to the demodulator. The weights are all set to one with the requirement that the channel gains are
approximately constant and this is usually achieved by using an automatic gain controller (AGC) in the system.
Some practical applications of EGC include the use of regenerative circuits to co-phase the received carriers.
However, the implementation of EGC diversity is cumbersome due to the additional circuitry required in order
to co-phase the signal in each branch.
V. CONCLUSION
WCDMA used for high data rates and allow more users to simultaneously access the network, but
performance of WCDMA is limited by interference, fading and scattering. In this review work various diversity
techniques were reviewed to overcome the fading problem. Each technique has its own unique advantage but in
comparison to other diversity techniques, maximum ratio combining technique is superior to other in many
aspects. The MRC technique has high diversity gain and high signal to noise ratio compared to other diversity
techniques.
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