This paper gives an overview about the various PHY and MAC layer specification which define
the IEEE 802.16 standard and which define the Fixed WiMAX (Ver. 802.16d-2004) and Mobile
WiMAX (Ver. 802.16e-2005) network scenarios. We also discuss about the various updates in
the Advanced Air Interface update (802.16m – 2011), which aims at fulfilling the 4G requirements as put forward by the ITU IMT-Advanced requirements.
Analysis of WiMAX Physical Layer Using Spatial Multiplexing Under Different F...CSCJournals
WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum and its industry. WiMAX is basically a wireless digital communication system which is also known as IEEE 802.16 standard intended for wireless \"metropolitan area networks\". WiMAX is based upon OFDM multiplexing technique. It was developed in order to provide high speed data rates to the users located in those areas also where broadband wireless coverage is not available. MIMO systems also play an important role in the field of wireless communication by allowing data to be transmitted and received over different antennas. WiMAX-MIMO systems are developed to improve the performance of WiMAX system. This paper analyzes WiMAX-MIMO system for different modulation schemes with different CC code rates under different fading channels (Rician and Nakagami channel). Spatial Multiplexing technique of MIMO system is used for the simulation purpose. Analysis has been done in the form of Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) plots.
IEEE 802.16 is a standard for fixed wireless broadband access that provides high-speed internet access over long distances (up to 31 miles). It uses point-to-multipoint radio links to connect base stations to multiple subscriber stations and supports services like data, voice, and video. The standard defines the physical and medium access control layers for both licensed and unlicensed frequency bands below 11GHz to support residential and small business broadband connectivity as a cheaper alternative to fiber.
The IEEE 802.16 work group originally covered wireless local loop technologies in the 10-11 GHz spectrum but later expanded the standards to include licensed and unlicensed spectra from 2-11 GHz. The WiMAX standards include 802.16-2004, which uses OFDM to serve multiple users in a round-robin fashion, and 802.16e, which uses OFDMA to simultaneously serve multiple users. WiMAX is designed to provide wireless broadband access as an alternative to cable and DSL using technologies like OFDM and adhering to principles such as supporting different network topologies and seamless integration with other wireless networks.
The document summarizes a lecture on wireless networks. It outlines the key requirements for wireless LANs including throughput, number of supported nodes, quality of service, energy saving, and roaming support. It also describes various wireless LAN technologies like infrared, UHF narrowband, and spread spectrum. Finally, it provides an overview of the IEEE 802.11 wireless LAN standard including the physical layers, bands, and data rates supported by different versions of the standard.
The document discusses several aspects of wireless local area networks (WLANs) including:
1. IEEE 802.11b is an enhancement of the original 802.11 standard that achieved data rates up to 11 Mbps using modifications to the physical layer.
2. IEEE 802.11a operates in the 5GHz band and supports data rates up to 54 Mbps using orthogonal frequency-division multiplexing (OFDM).
3. Many future developments are planned including enhancements to security, quality of service, and higher data rates above 100 Mbps.
This document contains 95 questions related to wireless networks and mobile communication systems. The questions cover topics such as infrared technology, spread spectrum techniques, IEEE 802.11, HIPERLAN, WiMax, mobile IP, routing protocols, UTRAN architecture, 3G UMTS network architecture, internetworking between WLAN and 3G networks, 4G features and challenges, orthogonal frequency division multiplexing, smart antenna techniques, LTE architecture, IMS architecture, and MVNO. The questions are divided into three parts - multiple choice questions, descriptive questions requiring short answers, and detailed descriptive questions requiring longer answers.
WiMAX (Worldwide Interoperability for Microwave Access) is a wireless communication standard based on the IEEE 802.16 set of standards that provide broadband wireless access. It uses OFDM modulation and operates in the 2-11 GHz range for fixed services and 2-6 GHz for mobile services. WiMAX has advantages like strong QoS, flexible architecture, and non-line-of-sight connections, but is limited to speeds up to 145 km/h for mobility. It has applications for military use in border surveillance, ship communications, and disaster relief operations.
WiMAX 2.0 is an update to the WiMAX standard that aims to provide higher data rates, lower latencies, and improved coverage compared to the original WiMAX 1.0 standard. It defines new physical and MAC layer specifications using OFDMA, supports carrier aggregation across multiple frequency bands, introduces advanced antenna techniques, and defines quality of service classes to efficiently allocate bandwidth. The document reviews the reasons for the WiMAX 2.0 update and key features such as increased data rates up to 1 Gbps, reduced framing overhead, support for heterogeneous networks, and enhanced interworking capabilities with other wireless technologies.
Analysis of WiMAX Physical Layer Using Spatial Multiplexing Under Different F...CSCJournals
WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum and its industry. WiMAX is basically a wireless digital communication system which is also known as IEEE 802.16 standard intended for wireless \"metropolitan area networks\". WiMAX is based upon OFDM multiplexing technique. It was developed in order to provide high speed data rates to the users located in those areas also where broadband wireless coverage is not available. MIMO systems also play an important role in the field of wireless communication by allowing data to be transmitted and received over different antennas. WiMAX-MIMO systems are developed to improve the performance of WiMAX system. This paper analyzes WiMAX-MIMO system for different modulation schemes with different CC code rates under different fading channels (Rician and Nakagami channel). Spatial Multiplexing technique of MIMO system is used for the simulation purpose. Analysis has been done in the form of Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) plots.
IEEE 802.16 is a standard for fixed wireless broadband access that provides high-speed internet access over long distances (up to 31 miles). It uses point-to-multipoint radio links to connect base stations to multiple subscriber stations and supports services like data, voice, and video. The standard defines the physical and medium access control layers for both licensed and unlicensed frequency bands below 11GHz to support residential and small business broadband connectivity as a cheaper alternative to fiber.
The IEEE 802.16 work group originally covered wireless local loop technologies in the 10-11 GHz spectrum but later expanded the standards to include licensed and unlicensed spectra from 2-11 GHz. The WiMAX standards include 802.16-2004, which uses OFDM to serve multiple users in a round-robin fashion, and 802.16e, which uses OFDMA to simultaneously serve multiple users. WiMAX is designed to provide wireless broadband access as an alternative to cable and DSL using technologies like OFDM and adhering to principles such as supporting different network topologies and seamless integration with other wireless networks.
The document summarizes a lecture on wireless networks. It outlines the key requirements for wireless LANs including throughput, number of supported nodes, quality of service, energy saving, and roaming support. It also describes various wireless LAN technologies like infrared, UHF narrowband, and spread spectrum. Finally, it provides an overview of the IEEE 802.11 wireless LAN standard including the physical layers, bands, and data rates supported by different versions of the standard.
The document discusses several aspects of wireless local area networks (WLANs) including:
1. IEEE 802.11b is an enhancement of the original 802.11 standard that achieved data rates up to 11 Mbps using modifications to the physical layer.
2. IEEE 802.11a operates in the 5GHz band and supports data rates up to 54 Mbps using orthogonal frequency-division multiplexing (OFDM).
3. Many future developments are planned including enhancements to security, quality of service, and higher data rates above 100 Mbps.
This document contains 95 questions related to wireless networks and mobile communication systems. The questions cover topics such as infrared technology, spread spectrum techniques, IEEE 802.11, HIPERLAN, WiMax, mobile IP, routing protocols, UTRAN architecture, 3G UMTS network architecture, internetworking between WLAN and 3G networks, 4G features and challenges, orthogonal frequency division multiplexing, smart antenna techniques, LTE architecture, IMS architecture, and MVNO. The questions are divided into three parts - multiple choice questions, descriptive questions requiring short answers, and detailed descriptive questions requiring longer answers.
WiMAX (Worldwide Interoperability for Microwave Access) is a wireless communication standard based on the IEEE 802.16 set of standards that provide broadband wireless access. It uses OFDM modulation and operates in the 2-11 GHz range for fixed services and 2-6 GHz for mobile services. WiMAX has advantages like strong QoS, flexible architecture, and non-line-of-sight connections, but is limited to speeds up to 145 km/h for mobility. It has applications for military use in border surveillance, ship communications, and disaster relief operations.
WiMAX 2.0 is an update to the WiMAX standard that aims to provide higher data rates, lower latencies, and improved coverage compared to the original WiMAX 1.0 standard. It defines new physical and MAC layer specifications using OFDMA, supports carrier aggregation across multiple frequency bands, introduces advanced antenna techniques, and defines quality of service classes to efficiently allocate bandwidth. The document reviews the reasons for the WiMAX 2.0 update and key features such as increased data rates up to 1 Gbps, reduced framing overhead, support for heterogeneous networks, and enhanced interworking capabilities with other wireless technologies.
The document discusses handover procedures in 4G networks. It describes handover basics and procedures in IEEE 802.16m and 3GPP LTE-Advanced networks. Advanced handover features in IEEE 802.16m like seamless handover and EBB handover are presented, along with legacy supported handover between IEEE 802.16m and 802.16e networks. Interworking handover procedures between IEEE 802.16m and 3GPP LTE-Advanced networks using layer 2 and layer 3 protocols are also summarized. The document concludes that advanced handover mechanisms in IMT-Advanced systems aim to reduce service interruption time and enhance user experience during handovers.
Multicarrier modulation is a technique for transmitting data over multiple carriers. It has advantages like resilience to interference and fading. One form is OFDM, which divides data over multiple orthogonal subcarriers. This avoids interference between carriers. OFDM is widely used in wireless technologies due to its spectral efficiency and resilience to multipath effects. Smart antennas and MIMO are techniques that use multiple antennas to improve wireless communication capabilities. IMS is an architectural framework that delivers multimedia services over an IP network for mobile phones. It contains elements like the HSS user database.
The document discusses 4G mobile communications standards including WiMAX and LTE. It provides information on:
- IEEE 802.22 which uses white spaces in TV frequencies for wireless regional area networks.
- Requirements for 4G standards defined by ITU including peak speeds of 1Gbps.
- How early versions of Mobile WiMAX and LTE did not meet the full 4G requirements but were still branded as 4G.
- Mobile WiMAX Release 2 and LTE Advanced promising speeds of 1Gbps in 2013.
This document provides an overview of wireless networks and the IEEE 802.11 standards. It discusses wireless LAN technologies including IEEE 802.11, HiperLAN, Bluetooth, and various amendments. It describes the infrastructure and ad-hoc modes of wireless LANs. It also summarizes key standards such as 802.11a, 802.11b, their architectures, protocols, and parameters. Finally, it provides details on the HiperLAN standard developed by ETSI for wireless local area networks in Europe.
Here are the solutions to the examples:
Example 21.5:
Let f(x) = x^3 - 3x^2 + 2x. Then,
f'(x) = 3x^2 - 6x + 2.
Example 21.6:
Let f(x) = 5x - 3. Then,
f'(x) = 5.
Example 21.7:
Let f(x) = sqrt(x). Then,
f'(x) = 1/(2sqrt(x)).
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This document summarizes the performance analysis of the physical (PHY) layer of WiMAX under different channel conditions. It provides details on the key components of WiMAX including the OFDM air interface, adaptive modulation and coding, and channel encoding. It also describes the simulation setup used to evaluate the PHY layer performance over varying wireless channel models.
EC 8004 wireless networks -Two marks with answersKannanKrishnana
The document discusses various aspects of wireless networks including infrared transmission, spread spectrum techniques, issues in wireless local area networks (WLAN), applications of WLAN, IEEE 802.11 standard, medium access control in IEEE 802.11, wireless asynchronous transfer mode (WATM), high performance radio local area network (HIPERLAN), Bluetooth, mobile IP, ad hoc networks, dynamic host configuration protocol (DHCP), session initiation protocol (SIP), orthogonal frequency division multiplexing (OFDM), and 4G and beyond technologies. Key topics covered are infrared and spread spectrum transmission methods, MAC functions in 802.11, requirements of HIPERLAN, states and modulation in Bluetooth, entities in mobile IP, characteristics
The document discusses the IEEE 802.16a standard for broadband wireless access and the role of WiMAX in driving adoption of the standard. The 802.16a standard specifies a protocol that supports applications like voice and video over wireless broadband, provides connectivity without line of sight, and can support hundreds to thousands of subscribers. WiMAX will help accelerate adoption of the standard by developing certification and interoperability test plans and awarding a "WiMAX Certified" label to certified equipment.
Design and analysis 5G mobile network model to enhancement high-density subsc...journalBEEI
To obtain a high data rate that is commensurate with the growing demand for internet services, the fifth generation (5G) cellular networks will use the bandwidth beyond 6 GHz, called millimeters waves (mm-waves), to obtain a higher. The first phase (phase I) of the 5G network design for high user density, where the optimized microcells are deployed at carrier frequency 700 MHz with 20 MHz bandwidth. The second phase (phase II) of the design consists of the deployment of microcells which are operating at 3.6 GHz with 100 MHz bandwidth; this phase is planned to cover 200000 users within the province. The third phase (phase III) of the design is represented by the deployment of picocells, which are planned to operate at 26 GHz frequency and bandwidth 500 MHz; this phase is planned to cover 3,500,000 users within the province. Two types of modulation are adopted for the network (orthogonal frequency division multiplexing (OFDM) and 256 quadrature amplitude modulation (QAM)); the overall performance of the network is studied with regards to the percentage of coverage, power overlapping ratio, frequency interference, and quality of service (QoS).
RF Analysis at Fiber-based Cell Sites with OBSAIEduardo Inzunza
1. The document discusses fiber-based cell site architectures that divide radio functions between a baseband unit (BBU) located at the base of the tower and remote radio heads (RRH) located by the antennas at the top of the tower, connected by interfaces like CPRI or OBSAI.
2. Testing distributed cell sites presents new challenges as RF maintenance requires accessing the RRH at the top of the tower. Solutions like CellAdvisor can characterize both RF and fiber signals and test quality from the ground using RFoCPRI/RFoOBSAI.
3. The OBSAI standard defines the architecture and RP3 interface between the BBU and RRH, including topologies like mesh
HIPERLAN was a wireless network standard developed in Europe as an alternative to IEEE 802.11. It aimed to provide higher data rates and quality of service compared to early 802.11 standards. HIPERLAN Type 1 achieved data rates up to 2Mbps in the 1990s. HIPERLAN Type 2 was developed later to support connection-oriented networking at up to 54Mbps, with quality of service, security, and flexibility to connect to different wired networks. While prototypes existed, commercial products were still in development in the early 2000s as the standard competed with improving 802.11 variants.
RF Analysis at Fiber-based Cell Sites with CPRIEduardo Inzunza
The document discusses the differences between conventional cell sites with coaxial cable connections from the radio equipment to antennas versus modern distributed cell sites with fiber optic connections. In distributed sites, the radio frequency functions are split between a baseband unit (BBU) located at the base of the tower and remote radio heads (RRH) located by the antennas. The common public radio interface (CPRI) standard defines the communication between BBUs and RRH over fiber. Maintaining distributed cell sites presents new challenges as any radio troubleshooting requires accessing equipment at the tower top.
The document provides an overview of LTE architecture and protocols. It describes the standardization landscape, LTE network architecture including elements like eNodeB, MME, S-GW and P-GW. It explains the user plane, control plane and management plane protocols in LTE. Specifically, it details the protocol stacks for each plane and the interfaces between different network elements like S1, S6a and X2. Finally, it discusses protocol overhead calculations in LTE.
This document summarizes an article from the International Journal of Computer Engineering and Technology that models and simulates the physical layer of the IEEE 802.22 wireless standard over a multipath fading channel. It describes the IEEE 802.22 standard and its use of OFDM and OFDMA to provide resilience against multipath propagation. It then models the physical layer in Simulink, including modulation, channel effects, demodulation and decoding. Finally, it presents simulation results for different modulation schemes and coding rates over multipath channels to analyze the performance of the physical layer under varying conditions.
This paper provides a high-level comparison
between LTE and WiMAX. The focus is on two primary areas: System Architecture and Physical Layer. The System Architecture describes the different functional elements in LTE and WiMAX and attempts to map similar functionality (such as mobility, security, access-gateway). We also compare and contrast the various aspects (such as transmission modes, duplexing types) of the physical layer.
Performance comparison of coded and uncoded ieee 802.16 d systems under stanf...IJCNCJournal
Worldwide Interoperability for Microwave Access (WiMax), standardized asIEEE 802.16d is a popular
technology for broadband wireless communication system. Orthogonal Frequency Division Multiplexing
(OFDM) is the core of this technology.OFDMreduces Inter-symbol Interference (ISI) and hence improves
system performance (i.e., Bit Error Rate (BER)). To improve system performance further error correction
coding schemes have been included in WiMax. It is widely accepted thata coded system outperforms an
uncodedsystem. But, the performance improvement of a coded system depends on the channel conditions. In
this paper, we investigated and compared the performances of a coded and an uncoded WiMaxsystem
under a practical channel model called Stanford University Interim (SUI). Different modulation schemes
namely BPSK, QPSK, 16-QAM, and 64-QAM have been considered in this work. It is shown that the
selection of codedoruncoded WiMaxsystem should depend on the channel condition as well as on the
modulation used. It is also shown that anuncoded system outperforms a coded system under some channel
conditions.
This document provides a comparative study of WiMAX and LTE networks. It summarizes key aspects of each network, including supported data rates and bandwidth, range, supported speeds, modulation techniques, frame structure, quality of service mechanisms, and security features. The document concludes with a comparison table highlighting that LTE supports higher data rates but shorter range compared to WiMAX, and different duplexing and frame allocation approaches between the two technologies.
The document provides information about Worldwide Interoperability for Microwave Access (WiMAX). It discusses the evolution of the IEEE 802.16 standard over time through various amendments. It also describes key features of WiMAX such as its use of OFDMA technology, quality of service capabilities, and ability to provide broadband wireless access over long distances.
This document provides an overview of the Mobile WiMAX IEEE 802.16m standard. It discusses key enhancements in Mobile WiMAX including improved non-line-of-sight coverage through advanced antenna diversity schemes and hybrid automatic repeat request. It also covers adaptive antenna systems and multiple-input multiple-output technologies to improve coverage. The document focuses on physical layer specifications for 802.16m including flexibility to support heterogeneous users and extending the use of multiple-input multiple-output transmission. It also discusses resource allocation, multi-cell multiple-input multiple-output, and interoperability with legacy WiMAX and other wireless technologies.
The document discusses the WiMAX (IEEE 802.16) wireless broadband standard. It provides an overview of the standard, including its physical layer specifications and MAC layer features. Key points covered include WiMAX targeting wireless broadband services up to 31 miles at over 100 Mbps, its use of OFDM and OFDMA technologies, support for QoS and different data protocols, and comparisons between WiMAX and Wi-Fi standards.
Simulation of IEEE 802.16e Physical LayerIOSR Journals
Abstract : Growth in technology has led to unprecedented demand for high speed Internet access. IEEE
802.16e (Mobile WiMAX) is a wireless communication standard with high data transfer rates and good
performance. It not only is efficient as compared to its counterpart technologies today (Wi-Fi and 3G), but also
lays the foundation for 4G mobile communication. In 4G wireless communication systems, bandwidth is a
precious resource, and service providers are continuously met with the challenge of accommodating more users
within a limited allocated bandwidth. To increase data rate of wireless medium with higher performance,
Mobile WiMAX uses Orthogonal Frequency Division Multiple Access (OFDMA). This paper describes the
simulation of the physical layer of IEEE 802.16e using Simulink in Matlab 7.0 (R2010a). The system
performance is evaluated considering the Signal to noise ratio (SNR) and Bit error rate (BER) parameters.
Keywords: 802.16e, OFDMA, Mobile WiMAX.
The document discusses handover procedures in 4G networks. It describes handover basics and procedures in IEEE 802.16m and 3GPP LTE-Advanced networks. Advanced handover features in IEEE 802.16m like seamless handover and EBB handover are presented, along with legacy supported handover between IEEE 802.16m and 802.16e networks. Interworking handover procedures between IEEE 802.16m and 3GPP LTE-Advanced networks using layer 2 and layer 3 protocols are also summarized. The document concludes that advanced handover mechanisms in IMT-Advanced systems aim to reduce service interruption time and enhance user experience during handovers.
Multicarrier modulation is a technique for transmitting data over multiple carriers. It has advantages like resilience to interference and fading. One form is OFDM, which divides data over multiple orthogonal subcarriers. This avoids interference between carriers. OFDM is widely used in wireless technologies due to its spectral efficiency and resilience to multipath effects. Smart antennas and MIMO are techniques that use multiple antennas to improve wireless communication capabilities. IMS is an architectural framework that delivers multimedia services over an IP network for mobile phones. It contains elements like the HSS user database.
The document discusses 4G mobile communications standards including WiMAX and LTE. It provides information on:
- IEEE 802.22 which uses white spaces in TV frequencies for wireless regional area networks.
- Requirements for 4G standards defined by ITU including peak speeds of 1Gbps.
- How early versions of Mobile WiMAX and LTE did not meet the full 4G requirements but were still branded as 4G.
- Mobile WiMAX Release 2 and LTE Advanced promising speeds of 1Gbps in 2013.
This document provides an overview of wireless networks and the IEEE 802.11 standards. It discusses wireless LAN technologies including IEEE 802.11, HiperLAN, Bluetooth, and various amendments. It describes the infrastructure and ad-hoc modes of wireless LANs. It also summarizes key standards such as 802.11a, 802.11b, their architectures, protocols, and parameters. Finally, it provides details on the HiperLAN standard developed by ETSI for wireless local area networks in Europe.
Here are the solutions to the examples:
Example 21.5:
Let f(x) = x^3 - 3x^2 + 2x. Then,
f'(x) = 3x^2 - 6x + 2.
Example 21.6:
Let f(x) = 5x - 3. Then,
f'(x) = 5.
Example 21.7:
Let f(x) = sqrt(x). Then,
f'(x) = 1/(2sqrt(x)).
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This document summarizes the performance analysis of the physical (PHY) layer of WiMAX under different channel conditions. It provides details on the key components of WiMAX including the OFDM air interface, adaptive modulation and coding, and channel encoding. It also describes the simulation setup used to evaluate the PHY layer performance over varying wireless channel models.
EC 8004 wireless networks -Two marks with answersKannanKrishnana
The document discusses various aspects of wireless networks including infrared transmission, spread spectrum techniques, issues in wireless local area networks (WLAN), applications of WLAN, IEEE 802.11 standard, medium access control in IEEE 802.11, wireless asynchronous transfer mode (WATM), high performance radio local area network (HIPERLAN), Bluetooth, mobile IP, ad hoc networks, dynamic host configuration protocol (DHCP), session initiation protocol (SIP), orthogonal frequency division multiplexing (OFDM), and 4G and beyond technologies. Key topics covered are infrared and spread spectrum transmission methods, MAC functions in 802.11, requirements of HIPERLAN, states and modulation in Bluetooth, entities in mobile IP, characteristics
The document discusses the IEEE 802.16a standard for broadband wireless access and the role of WiMAX in driving adoption of the standard. The 802.16a standard specifies a protocol that supports applications like voice and video over wireless broadband, provides connectivity without line of sight, and can support hundreds to thousands of subscribers. WiMAX will help accelerate adoption of the standard by developing certification and interoperability test plans and awarding a "WiMAX Certified" label to certified equipment.
Design and analysis 5G mobile network model to enhancement high-density subsc...journalBEEI
To obtain a high data rate that is commensurate with the growing demand for internet services, the fifth generation (5G) cellular networks will use the bandwidth beyond 6 GHz, called millimeters waves (mm-waves), to obtain a higher. The first phase (phase I) of the 5G network design for high user density, where the optimized microcells are deployed at carrier frequency 700 MHz with 20 MHz bandwidth. The second phase (phase II) of the design consists of the deployment of microcells which are operating at 3.6 GHz with 100 MHz bandwidth; this phase is planned to cover 200000 users within the province. The third phase (phase III) of the design is represented by the deployment of picocells, which are planned to operate at 26 GHz frequency and bandwidth 500 MHz; this phase is planned to cover 3,500,000 users within the province. Two types of modulation are adopted for the network (orthogonal frequency division multiplexing (OFDM) and 256 quadrature amplitude modulation (QAM)); the overall performance of the network is studied with regards to the percentage of coverage, power overlapping ratio, frequency interference, and quality of service (QoS).
RF Analysis at Fiber-based Cell Sites with OBSAIEduardo Inzunza
1. The document discusses fiber-based cell site architectures that divide radio functions between a baseband unit (BBU) located at the base of the tower and remote radio heads (RRH) located by the antennas at the top of the tower, connected by interfaces like CPRI or OBSAI.
2. Testing distributed cell sites presents new challenges as RF maintenance requires accessing the RRH at the top of the tower. Solutions like CellAdvisor can characterize both RF and fiber signals and test quality from the ground using RFoCPRI/RFoOBSAI.
3. The OBSAI standard defines the architecture and RP3 interface between the BBU and RRH, including topologies like mesh
HIPERLAN was a wireless network standard developed in Europe as an alternative to IEEE 802.11. It aimed to provide higher data rates and quality of service compared to early 802.11 standards. HIPERLAN Type 1 achieved data rates up to 2Mbps in the 1990s. HIPERLAN Type 2 was developed later to support connection-oriented networking at up to 54Mbps, with quality of service, security, and flexibility to connect to different wired networks. While prototypes existed, commercial products were still in development in the early 2000s as the standard competed with improving 802.11 variants.
RF Analysis at Fiber-based Cell Sites with CPRIEduardo Inzunza
The document discusses the differences between conventional cell sites with coaxial cable connections from the radio equipment to antennas versus modern distributed cell sites with fiber optic connections. In distributed sites, the radio frequency functions are split between a baseband unit (BBU) located at the base of the tower and remote radio heads (RRH) located by the antennas. The common public radio interface (CPRI) standard defines the communication between BBUs and RRH over fiber. Maintaining distributed cell sites presents new challenges as any radio troubleshooting requires accessing equipment at the tower top.
The document provides an overview of LTE architecture and protocols. It describes the standardization landscape, LTE network architecture including elements like eNodeB, MME, S-GW and P-GW. It explains the user plane, control plane and management plane protocols in LTE. Specifically, it details the protocol stacks for each plane and the interfaces between different network elements like S1, S6a and X2. Finally, it discusses protocol overhead calculations in LTE.
This document summarizes an article from the International Journal of Computer Engineering and Technology that models and simulates the physical layer of the IEEE 802.22 wireless standard over a multipath fading channel. It describes the IEEE 802.22 standard and its use of OFDM and OFDMA to provide resilience against multipath propagation. It then models the physical layer in Simulink, including modulation, channel effects, demodulation and decoding. Finally, it presents simulation results for different modulation schemes and coding rates over multipath channels to analyze the performance of the physical layer under varying conditions.
This paper provides a high-level comparison
between LTE and WiMAX. The focus is on two primary areas: System Architecture and Physical Layer. The System Architecture describes the different functional elements in LTE and WiMAX and attempts to map similar functionality (such as mobility, security, access-gateway). We also compare and contrast the various aspects (such as transmission modes, duplexing types) of the physical layer.
Performance comparison of coded and uncoded ieee 802.16 d systems under stanf...IJCNCJournal
Worldwide Interoperability for Microwave Access (WiMax), standardized asIEEE 802.16d is a popular
technology for broadband wireless communication system. Orthogonal Frequency Division Multiplexing
(OFDM) is the core of this technology.OFDMreduces Inter-symbol Interference (ISI) and hence improves
system performance (i.e., Bit Error Rate (BER)). To improve system performance further error correction
coding schemes have been included in WiMax. It is widely accepted thata coded system outperforms an
uncodedsystem. But, the performance improvement of a coded system depends on the channel conditions. In
this paper, we investigated and compared the performances of a coded and an uncoded WiMaxsystem
under a practical channel model called Stanford University Interim (SUI). Different modulation schemes
namely BPSK, QPSK, 16-QAM, and 64-QAM have been considered in this work. It is shown that the
selection of codedoruncoded WiMaxsystem should depend on the channel condition as well as on the
modulation used. It is also shown that anuncoded system outperforms a coded system under some channel
conditions.
This document provides a comparative study of WiMAX and LTE networks. It summarizes key aspects of each network, including supported data rates and bandwidth, range, supported speeds, modulation techniques, frame structure, quality of service mechanisms, and security features. The document concludes with a comparison table highlighting that LTE supports higher data rates but shorter range compared to WiMAX, and different duplexing and frame allocation approaches between the two technologies.
The document provides information about Worldwide Interoperability for Microwave Access (WiMAX). It discusses the evolution of the IEEE 802.16 standard over time through various amendments. It also describes key features of WiMAX such as its use of OFDMA technology, quality of service capabilities, and ability to provide broadband wireless access over long distances.
This document provides an overview of the Mobile WiMAX IEEE 802.16m standard. It discusses key enhancements in Mobile WiMAX including improved non-line-of-sight coverage through advanced antenna diversity schemes and hybrid automatic repeat request. It also covers adaptive antenna systems and multiple-input multiple-output technologies to improve coverage. The document focuses on physical layer specifications for 802.16m including flexibility to support heterogeneous users and extending the use of multiple-input multiple-output transmission. It also discusses resource allocation, multi-cell multiple-input multiple-output, and interoperability with legacy WiMAX and other wireless technologies.
The document discusses the WiMAX (IEEE 802.16) wireless broadband standard. It provides an overview of the standard, including its physical layer specifications and MAC layer features. Key points covered include WiMAX targeting wireless broadband services up to 31 miles at over 100 Mbps, its use of OFDM and OFDMA technologies, support for QoS and different data protocols, and comparisons between WiMAX and Wi-Fi standards.
Simulation of IEEE 802.16e Physical LayerIOSR Journals
Abstract : Growth in technology has led to unprecedented demand for high speed Internet access. IEEE
802.16e (Mobile WiMAX) is a wireless communication standard with high data transfer rates and good
performance. It not only is efficient as compared to its counterpart technologies today (Wi-Fi and 3G), but also
lays the foundation for 4G mobile communication. In 4G wireless communication systems, bandwidth is a
precious resource, and service providers are continuously met with the challenge of accommodating more users
within a limited allocated bandwidth. To increase data rate of wireless medium with higher performance,
Mobile WiMAX uses Orthogonal Frequency Division Multiple Access (OFDMA). This paper describes the
simulation of the physical layer of IEEE 802.16e using Simulink in Matlab 7.0 (R2010a). The system
performance is evaluated considering the Signal to noise ratio (SNR) and Bit error rate (BER) parameters.
Keywords: 802.16e, OFDMA, Mobile WiMAX.
SURVEYING BEST SUITABLE SCHEDULING ALGORITHM FOR WIMAX- WI-FI INTEGRATED HETE...cscpconf
To provide uninterrupted service to all subscribers in a wireless network, we need to incorporate a low cost, flexible Heterogeneous network which will be able to link with any kind
of network for efficient spectrum utilization, hence improved system capacity. In this connection, Wi-Fi/ Wi MAX integrated network seems to be an ideal solution as it is able to
provide easy deployment, high speed data rate and wide range coverage with high throughput, low end to end delay, flat and low jitter. Wi-Fi/ WiMAX integrated network provides Quality of
Service (QoS) that can support all kinds of real-time application in wireless networks that includes priority scheduling and queuing for bandwidth allocation that is based on traffic
scheduling algorithms within wireless networks. In this paper, we have designed a Wi-Fi/ WiMAX integrated network and analyze the performance of different scheduling algorithms for
that integrated network and highlight our findings on the scheduling algorithm which will give the best performance for a heterogeneous network.
This document provides an overview of the WiMAX standard 802.16, covering key concepts of OFDM transmission. It explains the evolution from 802.11 to 802.16e, describing standards such as 802.16, 802.16e, and WiBRO. The document also defines important OFDM terms, describes the 802.16 OFDM physical layer specifications, and explains the 802.16-2004 OFDMA frame structure and zone types.
This document discusses OFDM and the IEEE 802.16e physical layer standard. It provides an overview of OFDM concepts and how it works as a multi-carrier transmission technique. It then describes key aspects of the IEEE 802.16e standard including the different physical layer specifications for fixed, portable, and mobile WiMAX. It also discusses channel coding, modulation, cyclic prefix, and other elements of the OFDM signal transmission chain in the WiMAX system model.
The document discusses simulation of relay modes in IEEE 802.16j mobile multi-hop relay (MMR) WiMAX networks. It describes two relay modes defined in IEEE 802.16j - transparent mode and non-transparent mode. Transparent mode is used to increase capacity within the base station coverage area using two hops, while non-transparent mode extends base station coverage using two or more hops. The document outlines the simulation setup and parameters used to simulate both transparent and non-transparent relay modes in an IEEE 802.16j MMR network using the NCTUns simulation tool.
This document summarizes a presentation on WiMAX technology given by two students. It discusses how WiMAX uses OFDMA to provide broadband wireless access without direct line of sight, allowing for growth in broadband applications. It describes key features of WiMAX's physical and MAC layers that provide quality of service, scalability, and efficient service in multipath environments. These include flexible channelization, adaptive burst profiles, space-time coding for diversity, and a centralized scheduling MAC to ensure bandwidth efficiency and bounded delays.
This document is a paper presentation on WiMAX technology by D. Anusha R. Manasa and R. Manasa from Brahmaiah College of Engineering in Nellore, India. The paper provides an overview of WiMAX, including its benefits over other wireless technologies such as longer range without line of sight connectivity, higher data rates, and improved quality of service and scalability. Key features of the WiMAX physical and MAC layers that enhance performance in multipath environments are described. The paper concludes that WiMAX can complement existing networks by providing cost-effective broadband wireless access.
This document provides an overview of WiMAX technology, including the differences between fixed and mobile WiMAX. It discusses the IEEE 802.16 standards for fixed (802.16d) and mobile (802.16e) WiMAX. Fixed WiMAX uses OFDM and operates between 2-11 GHz for fixed wireless connections, while mobile WiMAX uses scalable OFDMA and enables handoffs between base stations for mobility below 100 km/h. Mobile WiMAX also introduces improved quality of service for real-time applications like voice. The document outlines the physical layer specifications and protocols of each standard.
This document discusses cost-effective deployment of relay stations in WiMAX networks. It first outlines the costs associated with base stations and relay stations, including capital expenditures and operational expenditures. It then discusses challenges in planning relay station placement to both improve quality of service and reduce costs. Specifically, it examines dividing the network into zones based on signal strength and using different modulation and coding schemes in each zone. The goal is to determine optimal relay station locations and configurations to enhance network performance while minimizing overall deployment costs.
The Performance Evaluation of IEEE 802.16 Physical Layer in the Basis of Bit ...IJCI JOURNAL
Fixed Broadband Wireless Access is a promising technology which can offer high speed data rate from transmitting end to customer end which can offer high speed text, voice, and video data. IEEE 802.16 WirelessMAN is a standard that specifies medium access control layer and a set of PHY layer to fixed and mobile BWA in broad range of frequencies and it supports equipment manufacturers due to its robust performance in multipath environment. Consequently WiMAX forum has adopted this version to develop the network world wide. In this paper the performance of IEEE 802.16 OFDM PHY Layer has been investigated by using the simulation model in Matlab. The Stanford University Interim (SUI) channel models are selected for the performance evaluation of this standard. The Ideal Channel estimation is considered in this work and the performance evaluation is observed in the basis of BER.
WiMAX is a wireless technology that provides broadband connections over long distances. It consists of towers that can provide coverage over large areas, and receivers that can connect devices like laptops. WiMAX provides both fixed and mobile services defined by IEEE 802.16 standards. Fixed WiMAX uses various antenna types to optimize coverage for non-mobile users, while Mobile WiMAX allows subscribers to roam between towers. WiMAX has advantages over wired broadband in supporting high-speed data transfer over longer ranges at a lower cost.
The document describes WiMAX technology and compares it to WiFi. It discusses the IEEE 802.16 standard that WiMAX is based on and the two versions: fixed and mobile. It also reviews some non-standard commercial solutions for wireless networks like Alvarion, Motorola Canopy, and MikroTik that have been used for medium to long-range networks.
This document discusses WiMAX (Worldwide Interoperability for Microwave Access), a wireless technology based on IEEE 802.16 standards that can provide broadband connections over long distances. It defines key terms, describes applications of WiMAX for both fixed and mobile use, how WiMAX systems work, competing technologies, current deployments, benefits compared to other options, and initiatives to bring WiMAX to Pakistan.
This document summarizes several wireless networking standards and protocols used in IoT applications. It discusses protocols for different layers including transport, discovery, data, and device management. Specific standards covered include 6LoWPAN, EPC, WiFi, Bluetooth, ZigBee, and different versions of WiFi (802.11b, 802.11g, 802.11a, 802.11n). Key differences between the standards are highlighted such as operating frequency bands, maximum data rates, and effective transmission ranges. The document provides an overview of the organizational layers in which various IoT protocols operate and the rapid development of new protocols to meet diverse IoT requirements.
802.16e provides enhancements to 802.16-2004 to support subscriber stations moving at vehicular speeds. It specifies a system for combined fixed and mobile broadband wireless access using Scalable OFDMA technology. Mobile WiMAX supports seamless handoff between base stations, sleep and idle modes for power management, and smart antenna technologies like beamforming. It can offer full mobility and compete with 3G for IP traffic with peak data rates up to 63Mbps download and 28Mbps upload in a 10MHz channel.
This document provides an overview and summary of WiMAX technology. It discusses:
1) WiMAX is a wireless technology that provides broadband connectivity without direct line-of-sight to a base station, addressing the need for higher bandwidth applications. It uses OFDM/OFDMA to divide spectrum into sub-carriers.
2) Key differences between WiMAX (IEEE 802.16) and other technologies like WiFi include greater bandwidth, encryption, and ability to support both indoor and outdoor use cases.
3) The PHY and MAC layers of WiMAX were designed to scale from one to hundreds of users per channel and provide quality of service, addressing limitations of technologies like WiFi.
This document provides an overview of wireless communication standards including IEEE 802.11x, 802.15x, and 802.16x. It discusses the objectives of the unit which are to explain the differences between wireless LANs, PANs, and MANs. It then goes on to describe the evolution of IEEE 802.11 standards including improvements to data rates, security, and quality of service over time. Key standards such as 802.11a, 802.11b, 802.11g, and 802.11n are explained. Design challenges for wireless LANs like changing topologies and interference are also summarized.
Similar to Next Generation 4G WiMAX Networks - IEEE 802.16 Standard: (20)
ANALYSIS OF LAND SURFACE DEFORMATION GRADIENT BY DINSAR cscpconf
The progressive development of Synthetic Aperture Radar (SAR) systems diversify the exploitation of the generated images by these systems in different applications of geoscience. Detection and monitoring surface deformations, procreated by various phenomena had benefited from this evolution and had been realized by interferometry (InSAR) and differential interferometry (DInSAR) techniques. Nevertheless, spatial and temporal decorrelations of the interferometric couples used, limit strongly the precision of analysis results by these techniques. In this context, we propose, in this work, a methodological approach of surface deformation detection and analysis by differential interferograms to show the limits of this technique according to noise quality and level. The detectability model is generated from the deformation signatures, by simulating a linear fault merged to the images couples of ERS1 / ERS2 sensors acquired in a region of the Algerian south.
4D AUTOMATIC LIP-READING FOR SPEAKER'S FACE IDENTIFCATIONcscpconf
A novel based a trajectory-guided, concatenating approach for synthesizing high-quality image real sample renders video is proposed . The lips reading automated is seeking for modeled the closest real image sample sequence preserve in the library under the data video to the HMM predicted trajectory. The object trajectory is modeled obtained by projecting the face patterns into an KDA feature space is estimated. The approach for speaker's face identification by using synthesise the identity surface of a subject face from a small sample of patterns which sparsely each the view sphere. An KDA algorithm use to the Lip-reading image is discrimination, after that work consisted of in the low dimensional for the fundamental lip features vector is reduced by using the 2D-DCT.The mouth of the set area dimensionality is ordered by a normally reduction base on the PCA to obtain the Eigen lips approach, their proposed approach by[33]. The subjective performance results of the cost function under the automatic lips reading modeled , which wasn’t illustrate the superior performance of the
method.
MOVING FROM WATERFALL TO AGILE PROCESS IN SOFTWARE ENGINEERING CAPSTONE PROJE...cscpconf
Universities offer software engineering capstone course to simulate a real world-working environment in which students can work in a team for a fixed period to deliver a quality product. The objective of the paper is to report on our experience in moving from Waterfall process to Agile process in conducting the software engineering capstone project. We present the capstone course designs for both Waterfall driven and Agile driven methodologies that highlight the structure, deliverables and assessment plans.To evaluate the improvement, we conducted a survey for two different sections taught by two different instructors to evaluate students’ experience in moving from traditional Waterfall model to Agile like process. Twentyeight students filled the survey. The survey consisted of eight multiple-choice questions and an open-ended question to collect feedback from students. The survey results show that students were able to attain hands one experience, which simulate a real world-working environment. The results also show that the Agile approach helped students to have overall better design and avoid mistakes they have made in the initial design completed in of the first phase of the capstone project. In addition, they were able to decide on their team capabilities, training needs and thus learn the required technologies earlier which is reflected on the final product quality
PROMOTING STUDENT ENGAGEMENT USING SOCIAL MEDIA TECHNOLOGIEScscpconf
This document discusses using social media technologies to promote student engagement in a software project management course. It describes the course and objectives of enhancing communication. It discusses using Facebook for 4 years, then switching to WhatsApp based on student feedback, and finally introducing Slack to enable personalized team communication. Surveys found students engaged and satisfied with all three tools, though less familiar with Slack. The conclusion is that social media promotes engagement but familiarity with the tool also impacts satisfaction.
A SURVEY ON QUESTION ANSWERING SYSTEMS: THE ADVANCES OF FUZZY LOGICcscpconf
In real world computing environment with using a computer to answer questions has been a human dream since the beginning of the digital era, Question-answering systems are referred to as intelligent systems, that can be used to provide responses for the questions being asked by the user based on certain facts or rules stored in the knowledge base it can generate answers of questions asked in natural , and the first main idea of fuzzy logic was to working on the problem of computer understanding of natural language, so this survey paper provides an overview on what Question-Answering is and its system architecture and the possible relationship and
different with fuzzy logic, as well as the previous related research with respect to approaches that were followed. At the end, the survey provides an analytical discussion of the proposed QA models, along or combined with fuzzy logic and their main contributions and limitations.
DYNAMIC PHONE WARPING – A METHOD TO MEASURE THE DISTANCE BETWEEN PRONUNCIATIONS cscpconf
Human beings generate different speech waveforms while speaking the same word at different times. Also, different human beings have different accents and generate significantly varying speech waveforms for the same word. There is a need to measure the distances between various words which facilitate preparation of pronunciation dictionaries. A new algorithm called Dynamic Phone Warping (DPW) is presented in this paper. It uses dynamic programming technique for global alignment and shortest distance measurements. The DPW algorithm can be used to enhance the pronunciation dictionaries of the well-known languages like English or to build pronunciation dictionaries to the less known sparse languages. The precision measurement experiments show 88.9% accuracy.
INTELLIGENT ELECTRONIC ASSESSMENT FOR SUBJECTIVE EXAMS cscpconf
In education, the use of electronic (E) examination systems is not a novel idea, as Eexamination systems have been used to conduct objective assessments for the last few years. This research deals with randomly designed E-examinations and proposes an E-assessment system that can be used for subjective questions. This system assesses answers to subjective questions by finding a matching ratio for the keywords in instructor and student answers. The matching ratio is achieved based on semantic and document similarity. The assessment system is composed of four modules: preprocessing, keyword expansion, matching, and grading. A survey and case study were used in the research design to validate the proposed system. The examination assessment system will help instructors to save time, costs, and resources, while increasing efficiency and improving the productivity of exam setting and assessments.
TWO DISCRETE BINARY VERSIONS OF AFRICAN BUFFALO OPTIMIZATION METAHEURISTICcscpconf
African Buffalo Optimization (ABO) is one of the most recent swarms intelligence based metaheuristics. ABO algorithm is inspired by the buffalo’s behavior and lifestyle. Unfortunately, the standard ABO algorithm is proposed only for continuous optimization problems. In this paper, the authors propose two discrete binary ABO algorithms to deal with binary optimization problems. In the first version (called SBABO) they use the sigmoid function and probability model to generate binary solutions. In the second version (called LBABO) they use some logical operator to operate the binary solutions. Computational results on two knapsack problems (KP and MKP) instances show the effectiveness of the proposed algorithm and their ability to achieve good and promising solutions.
DETECTION OF ALGORITHMICALLY GENERATED MALICIOUS DOMAINcscpconf
In recent years, many malware writers have relied on Dynamic Domain Name Services (DDNS) to maintain their Command and Control (C&C) network infrastructure to ensure a persistence presence on a compromised host. Amongst the various DDNS techniques, Domain Generation Algorithm (DGA) is often perceived as the most difficult to detect using traditional methods. This paper presents an approach for detecting DGA using frequency analysis of the character distribution and the weighted scores of the domain names. The approach’s feasibility is demonstrated using a range of legitimate domains and a number of malicious algorithmicallygenerated domain names. Findings from this study show that domain names made up of English characters “a-z” achieving a weighted score of < 45 are often associated with DGA. When a weighted score of < 45 is applied to the Alexa one million list of domain names, only 15% of the domain names were treated as non-human generated.
GLOBAL MUSIC ASSET ASSURANCE DIGITAL CURRENCY: A DRM SOLUTION FOR STREAMING C...cscpconf
The document proposes a blockchain-based digital currency and streaming platform called GoMAA to address issues of piracy in the online music streaming industry. Key points:
- GoMAA would use a digital token on the iMediaStreams blockchain to enable secure dissemination and tracking of streamed content. Content owners could control access and track consumption of released content.
- Original media files would be converted to a Secure Portable Streaming (SPS) format, embedding watermarks and smart contract data to indicate ownership and enable validation on the blockchain.
- A browser plugin would provide wallets for fans to collect GoMAA tokens as rewards for consuming content, incentivizing participation and addressing royalty discrepancies by recording
IMPORTANCE OF VERB SUFFIX MAPPING IN DISCOURSE TRANSLATION SYSTEMcscpconf
This document discusses the importance of verb suffix mapping in discourse translation from English to Telugu. It explains that after anaphora resolution, the verbs must be changed to agree with the gender, number, and person features of the subject or anaphoric pronoun. Verbs in Telugu inflect based on these features, while verbs in English only inflect based on number and person. Several examples are provided that demonstrate how the Telugu verb changes based on whether the subject or pronoun is masculine, feminine, neuter, singular or plural. Proper verb suffix mapping is essential for generating natural and coherent translations while preserving the context and meaning of the original discourse.
EXACT SOLUTIONS OF A FAMILY OF HIGHER-DIMENSIONAL SPACE-TIME FRACTIONAL KDV-T...cscpconf
In this paper, based on the definition of conformable fractional derivative, the functional
variable method (FVM) is proposed to seek the exact traveling wave solutions of two higherdimensional
space-time fractional KdV-type equations in mathematical physics, namely the
(3+1)-dimensional space–time fractional Zakharov-Kuznetsov (ZK) equation and the (2+1)-
dimensional space–time fractional Generalized Zakharov-Kuznetsov-Benjamin-Bona-Mahony
(GZK-BBM) equation. Some new solutions are procured and depicted. These solutions, which
contain kink-shaped, singular kink, bell-shaped soliton, singular soliton and periodic wave
solutions, have many potential applications in mathematical physics and engineering. The
simplicity and reliability of the proposed method is verified.
AUTOMATED PENETRATION TESTING: AN OVERVIEWcscpconf
The document discusses automated penetration testing and provides an overview. It compares manual and automated penetration testing, noting that automated testing allows for faster, more standardized and repeatable tests but has limitations in developing new exploits. It also reviews some current automated penetration testing methodologies and tools, including those using HTTP/TCP/IP attacks, linking common scanning tools, a Python-based tool targeting databases, and one using POMDPs for multi-step penetration test planning under uncertainty. The document concludes that automated testing is more efficient than manual for known vulnerabilities but cannot replace manual testing for discovering new exploits.
CLASSIFICATION OF ALZHEIMER USING fMRI DATA AND BRAIN NETWORKcscpconf
Since the mid of 1990s, functional connectivity study using fMRI (fcMRI) has drawn increasing
attention of neuroscientists and computer scientists, since it opens a new window to explore
functional network of human brain with relatively high resolution. BOLD technique provides
almost accurate state of brain. Past researches prove that neuro diseases damage the brain
network interaction, protein- protein interaction and gene-gene interaction. A number of
neurological research paper also analyse the relationship among damaged part. By
computational method especially machine learning technique we can show such classifications.
In this paper we used OASIS fMRI dataset affected with Alzheimer’s disease and normal
patient’s dataset. After proper processing the fMRI data we use the processed data to form
classifier models using SVM (Support Vector Machine), KNN (K- nearest neighbour) & Naïve
Bayes. We also compare the accuracy of our proposed method with existing methods. In future,
we will other combinations of methods for better accuracy.
VALIDATION METHOD OF FUZZY ASSOCIATION RULES BASED ON FUZZY FORMAL CONCEPT AN...cscpconf
The document proposes a new validation method for fuzzy association rules based on three steps: (1) applying the EFAR-PN algorithm to extract a generic base of non-redundant fuzzy association rules using fuzzy formal concept analysis, (2) categorizing the extracted rules into groups, and (3) evaluating the relevance of the rules using structural equation modeling, specifically partial least squares. The method aims to address issues with existing fuzzy association rule extraction algorithms such as large numbers of extracted rules, redundancy, and difficulties with manual validation.
PROBABILITY BASED CLUSTER EXPANSION OVERSAMPLING TECHNIQUE FOR IMBALANCED DATAcscpconf
In many applications of data mining, class imbalance is noticed when examples in one class are
overrepresented. Traditional classifiers result in poor accuracy of the minority class due to the
class imbalance. Further, the presence of within class imbalance where classes are composed of
multiple sub-concepts with different number of examples also affect the performance of
classifier. In this paper, we propose an oversampling technique that handles between class and
within class imbalance simultaneously and also takes into consideration the generalization
ability in data space. The proposed method is based on two steps- performing Model Based
Clustering with respect to classes to identify the sub-concepts; and then computing the
separating hyperplane based on equal posterior probability between the classes. The proposed
method is tested on 10 publicly available data sets and the result shows that the proposed
method is statistically superior to other existing oversampling methods.
CHARACTER AND IMAGE RECOGNITION FOR DATA CATALOGING IN ECOLOGICAL RESEARCHcscpconf
Data collection is an essential, but manpower intensive procedure in ecological research. An
algorithm was developed by the author which incorporated two important computer vision
techniques to automate data cataloging for butterfly measurements. Optical Character
Recognition is used for character recognition and Contour Detection is used for imageprocessing.
Proper pre-processing is first done on the images to improve accuracy. Although
there are limitations to Tesseract’s detection of certain fonts, overall, it can successfully identify
words of basic fonts. Contour detection is an advanced technique that can be utilized to
measure an image. Shapes and mathematical calculations are crucial in determining the precise
location of the points on which to draw the body and forewing lines of the butterfly. Overall,
92% accuracy were achieved by the program for the set of butterflies measured.
SOCIAL MEDIA ANALYTICS FOR SENTIMENT ANALYSIS AND EVENT DETECTION IN SMART CI...cscpconf
Smart cities utilize Internet of Things (IoT) devices and sensors to enhance the quality of the city
services including energy, transportation, health, and much more. They generate massive
volumes of structured and unstructured data on a daily basis. Also, social networks, such as
Twitter, Facebook, and Google+, are becoming a new source of real-time information in smart
cities. Social network users are acting as social sensors. These datasets so large and complex
are difficult to manage with conventional data management tools and methods. To become
valuable, this massive amount of data, known as 'big data,' needs to be processed and
comprehended to hold the promise of supporting a broad range of urban and smart cities
functions, including among others transportation, water, and energy consumption, pollution
surveillance, and smart city governance. In this work, we investigate how social media analytics
help to analyze smart city data collected from various social media sources, such as Twitter and
Facebook, to detect various events taking place in a smart city and identify the importance of
events and concerns of citizens regarding some events. A case scenario analyses the opinions of
users concerning the traffic in three largest cities in the UAE
SOCIAL NETWORK HATE SPEECH DETECTION FOR AMHARIC LANGUAGEcscpconf
The anonymity of social networks makes it attractive for hate speech to mask their criminal
activities online posing a challenge to the world and in particular Ethiopia. With this everincreasing
volume of social media data, hate speech identification becomes a challenge in
aggravating conflict between citizens of nations. The high rate of production, has become
difficult to collect, store and analyze such big data using traditional detection methods. This
paper proposed the application of apache spark in hate speech detection to reduce the
challenges. Authors developed an apache spark based model to classify Amharic Facebook
posts and comments into hate and not hate. Authors employed Random forest and Naïve Bayes
for learning and Word2Vec and TF-IDF for feature selection. Tested by 10-fold crossvalidation,
the model based on word2vec embedding performed best with 79.83%accuracy. The
proposed method achieve a promising result with unique feature of spark for big data.
GENERAL REGRESSION NEURAL NETWORK BASED POS TAGGING FOR NEPALI TEXTcscpconf
This article presents Part of Speech tagging for Nepali text using General Regression Neural
Network (GRNN). The corpus is divided into two parts viz. training and testing. The network is
trained and validated on both training and testing data. It is observed that 96.13% words are
correctly being tagged on training set whereas 74.38% words are tagged correctly on testing
data set using GRNN. The result is compared with the traditional Viterbi algorithm based on
Hidden Markov Model. Viterbi algorithm yields 97.2% and 40% classification accuracies on
training and testing data sets respectively. GRNN based POS Tagger is more consistent than the
traditional Viterbi decoding technique.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Reimagining Your Library Space: How to Increase the Vibes in Your Library No ...Diana Rendina
Librarians are leading the way in creating future-ready citizens – now we need to update our spaces to match. In this session, attendees will get inspiration for transforming their library spaces. You’ll learn how to survey students and patrons, create a focus group, and use design thinking to brainstorm ideas for your space. We’ll discuss budget friendly ways to change your space as well as how to find funding. No matter where you’re at, you’ll find ideas for reimagining your space in this session.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
2. 508 Computer Science & Information Technology ( CS & IT )
The standard specifies the air interface of BWA, which include the Medium Access Control
(MAC) and Physical (PHY) layers. The chief advancement of the PHY layer includes orthogonal
frequency-division multiplexing (OFDM), in which multiple access is achieved by assigning a
subset of subcarriers for each individual user. With advances in standards including the 802.16e
support for advanced antenna system (AAS) through MIMO technology, which uses multiple
antennas at both transmitter and receiver, which sets up a multiple data stream on the same
channel, increasing the data capacity of the channel to a great extent. The MAC layer uses a
scheduling algorithm which determines access between subscriber station and base station. It also
provides control of Quality of Service (QoS) parameters through the base station.
The next evolutionary update of the IEEE 802.16 standard is the IEEE 802.16m (802.16-2011)
also known as WiMAX rel 2.0.Building upon the IEEE 802.16e or mobile WiMAX, this standard
is accepted candidate for the IMT-Advanced specifications provided by the ITU. Like its previous
version, IEEE 802.16m uses OFDMA as multiple access scheme, with support for TDD, FDD
and half duplex FDD. The fundamental concept of WiMAX remains the same , but in order to
meet the IMT-Advanced specifications many technical updates are provided, which aim for
higher efficiencies in PHY and MAC layer and environment optimised deployments, as well as
high data rates and low packet latencies.
2. WIMAX IEEE 802.16 PHYSICAL LAYER:
The IEEE 802.16 physical layer uses a number of legacy technologies which include Orthogonal
Frequency Division Multiplexing (OFDM), Time Division Duplexing (TDD), Frequency
Division Duplexing (FDD), Adaptive Modulation and Coding (AMC), and Adaptive Antenna
System (AAS). AMC with 16 different modulation and coding schemes is used to manage fine
granularity of link adaption mechanism. Multi-Carrier operation is used to enable ―virtualǁ
carriers up to 100MHz wide and for deployments in radio spectrum for carriers other than 5, 10
and 20 MHZ.
2.1 OFDM-based air interface:
The WiMAX air interface (PHY Layer) is based on Orthogonal Frequency Division Multiplexing.
To maintain orthogonality between the individual carriers the symbol period must be reciprocal of
the carrier spacing. OFDM is a form of multi-carrier modulation, which divides a high bit stream
into a number of low bit streams, which are each modulated by separate carriers called subcarriers
or tones. These modulation schemes generally remove Inter Symbol Interference by keeping the
symbol duration large. But for high data rate systems where the symbol duration is small, the high
bit stream is splitted into several parallel streams increasing the symbol duration of each stream.
The sub-carriers are chosen such that they are orthogonal; hence there is no mutual interference
among the signal streams.
The IEEE 802.16 standard supports number of physical layer specifications. The first version of
this standard only supported single carrier modulation in in licensed spectrum of 10-66 GHZ in
LOS operations. With addition of OFDM, OFDMA and scalable OFDMA, IEEE 802.16
operation also includes NLOS and also provides mobility.
The range of frequencies supported in the licensed as well as unlicensed bands for IEEE 802.16 is
as described below:
• 10–66 GHz licensed band – IEEE 802.16-2004 defines the PHY layer for the 10–66 GHz
licensed spectrum. Operation in LOS environment.
• 2–11 GHz licensed and licensed exempt – In this frequency bands, both licensed and
licensed exempt bands are addressed. Additional features help in operation of NLOS and
LOS environment also reduce the effects of multi path propagation.
3. Computer Science & Information Technology ( CS & IT ) 509
• WirelessMAN-SC PHY mode of IEEE 802.16-2004 supports operation in the 10–66 GHz
frequency band. At these frequencies LOS operation is more practical. This mode is an
adaptive modulation scheme (QPSK, 16-QAM, 64-QAM) on a single carrier. Duplexing
support is by TDD or FDD.
• The WirelessMAN-OFDM PHY is based on Orthogonal Frequency Division
Multiplexing (OFDM) modulation. It has been designed for NLOS operation in
frequency band 2-11 GHZ. It uses 256-point transform in OFDM access is by TDMA.
Operates on license exempt bands
IEEE 802.16 air interface specifications
WirelessMAN-OFDMA is among the three specifications defined in IEEE 802.16 family for
applications below 11 GHz. The IEEE 802.16e-2005 amendment was developed to extend the
802.16 Air Interface Standard to cover mobile applications. This uses orthogonal frequency-
division multiple access with a 2048-point transform and is designed for NLOS operation in the
frequency bands below 11 GHz. In the OFDMA mode, the active subcarriers are divided into
subsets of subcarriers, where each subset is termed a sub channel. In the downlink, a sub channel
may be intended for different receiver(s); In the uplink a sub channel may be assigned for
different transmitter(s).This sub channels may not be adjacent.
The 802.16e-2005 standard gives three sub channel allocation based on usage environments:
• Subcarriers can be scattered throughout the frequency channel range. This is referred to
as fully used sub channelization or FUSC.
• Several scattered clusters of subcarriers can be used to form a sub channel. This is
referred to as partially used sub channelization or PUSC.
• Sub channels can be composed of contiguous groups of subcarriers. This is referred to as
adaptive modulation and coding or AMC.
4. 510 Computer Science & Information Technology ( CS & IT )
OFDMA sub channel description
2.1.1 Support for heterogeneous users in IEEE 802.16m update:
One of the main objectives of future wireless system is to able to provide efficient and flexible
services to users of different needs. For some users low data rates but a reliable link is preferred,
while some users require high data rates, even if delays from retransmissions can occur.
Moreover the co-existence should have low overheard on the systems. Hence under the IEEE
802.16m update, frame structure has been modified with reference to the 802.16e. The frame
structure of the 80216e consists of a downlink and an uplink part separated by OFDMA symbols
of variable size. The frame structure under 802.16m is given below:
Data is organized into a hierarchy of superframes, frames, subframes and OFDM symbols. Each
superframe last 20 ms and contains four 5ms frames. Each of these 5ms frames contains 8
subframes. However if the channel size is 7 MHZ in which case frames contain 6 subframes, or
8.75 MHZ, in which case frames contain 7 subframes. Subframes fall into one of four categories,
three of which are employed as part of 802.16m and a fourth that is included for legacy operation
with 802.16-2009 devices operating on 8.75 MHz channels. There are four types of subframes:
Type-1 has 6 OFDMA symbols; Type-2 has 7 OFDMA symbols; Type-3 has 6 OFDMA
symbols; Type -4 has 9 OFDMA symbols and is included for legacy operation with 802.16-2009
devices operating on 8.75 MHz channels.
Frame structure with Type-1 subframe
2.2 Adaptive Antenna Systems (AAS):
Adaptive Antenna Systems (AAS) uses beam-forming techniques to focus the wireless beam
between the base station and the subscriber. Under beam-forming multiple antennas and multiple
signals are employed, which then shape the beam with the intent of improving transmission to the
desired station. The result is reduced interference because the signal going to the desired user is
increased and the signal going to other users is reduced. Dynamic Frequency Selection (DFS)
5. Computer Science & Information Technology ( CS & IT ) 511
schemes are applied in which air waves are first scanned to determine where interference doesn’t
occur, and specific frequencies in that area where no interference occurs is selected. These are
achieved in WiMAX through the use of MIMO (multiple-input multiple output) communication
schemes. MIMO uses multiple antennas at both transmitter and receiver, which sets up a multiple
data stream on the same channel, increasing the data capacity of the channel to a great extent.
With multiple antennas at both transmitter and receiver, the transmitter and receiver can
coordinate to move to an open frequency if/when interference occurs. In application, the MIMO
technology can be divided based on Open Loop MIMO techniques and Closed Loop MIMO
techniques. MIMO systems that do not rely on knowledge of the channel responses at the
transmitter are open loop. Closed loop is the case when the channel state information (CSI) is
available at the transmitter through some form of feedback mechanism.
2.2.1 Extended Use of MIMO under 802.16m:
IEEE 802.16m supports several advanced multi-antenna techniques including single and multi-
user MIMO (spatial multiplexing and beam-forming) as well as a number of transmit diversity
schemes. In single-user MIMO (SU-MIMO) scheme only one user can be scheduled over one
resource unit, while in multi-user MIMO (MU-MIMO), multiple users can be scheduled in one
resource unit.Moreover, although some other MIMO features of 802.16e, such as closed-loop
MIMO, have not appeared in Mobile WiMAX profiles yet, it is expected that they will be
included in new 802.16m-based systems. More specifically, it has been already decided to
support closed-loop MIMO using Channel Quality Information, Precoding Matrix Index and rank
feedback in future systems.
IEEE 802.16e and 802.16m Requirements
Single-user MIMO (SU-MIMO) schemes are used to improve the link performance, by providing
robust transmissions with spatial diversity, or large spatial multiplexing gain and peak data rate to
a single MS, or beamforming gain. Both open-loop SU-MIMO and closed-loop SU-MIMO is
supported in 16m. For open-loop SU-MIMO, both spatial multiplexing and transmit diversity
6. 512 Computer Science & Information Technology ( CS & IT )
schemes are supported. For closed-loop SU-MIMO, codebook based precoding is supported for
both TDD and FDD systems.
Multi-user MIMO (MU-MIMO) schemes are used to enable resource allocation to communicate
data to two or more mobile stations. MU-MIMO enhances the system throughput. Multi-user
transmission with one stream per user is supported in MU-MIMO mode. MU-MIMO includes the
MIMO configuration of 2 Transmit antennas to support up to 2 users, and 4 Transmit or 8
Transmit antennas to support up to 4 users. Both unitary and non-unitary MU-MIMO linear
precoding techniques are supported. For open-loop MU-MIMO, channel quality indicator (CQI)
and preferred stream index feedback may be transmitted to assist the base station’s scheduling,
transmission mode switching, and rate adaptation. The CQI is frequency dependent. For closed-
loop multi -user MIMO, codebook based precoding is supported for both TDD and FDD systems.
CQI and PMI feedback can be transmitted by the mobile station to assist the base station’s
scheduling, resource allocation, and rate adaptation decisions.
2.3 Adaptive Modulation and Coding (AMC):
WiMAX supports a variety of modulation and coding schemes. These schemes are adaptive, and
can hence be made to vary its parameters, according to the prevalent conditions. WiMAX
modulation and coding can be made to change on a burst by burst basis per link. The coding and
modulation schemes maintain a steady signal strength by using different schemes over increasing
distance; this is achieved by decreasing throughput over range so as to provide the best Quality of
Service (QoS) possible over distance. Also, a technique called Dynamic Bandwidth Allocation
(DBA) is used, which monitors the network for interference or reduction in signal strength, the
base station allocates more bandwidth to the afflicted stream. To determine the required WiMAX
modulation and coding scheme the channel quality feedback indicator is used. The mobile (UE)
can provide the base station (BS) with feedback on the downlink channel quality and for the
uplink, the base station can estimate the channel quality, based on the received signal quality.
Adaptive Modulation under WiMAX
The various modulation schemes used under WiMAX:
Downlink: BPSK, QPSK, 16 QAM, 64 QAM; BPSK optional for OFDM-PHY.
Uplink: BPSK, QPSK, 16 QAM; 64 QAM optional.
The various coding schemes used under WiMAX:
Downlink: convolutional codes at 1/2, 2/3, 3/4, 5/6
7. Computer Science & Information Technology ( CS & IT ) 513
Uplink: convolutional codes at 1/2, 2/3, 3/4, 5/6
In telecommunication, convolutional codes are like error-correcting codes, in which each m-bit
information bit is to be transformed into an n-bit symbol where m/n is the code rate (n ≥ m).the
transformation is a function of last information k information symbol, where k is a the constraint
length of the symbol.
3. WIMAX IEEE 802.16 MAC LAYER:
Medium Access Control or MAC layer lies above the PHY layer of the open system interconnect
(OSI) protocol stack layers. Its primary objective is to provide an interface between the higher
transport layers and the lower physical layer. The MAC layer takes packets from the upper layer,
these packets are called MAC service data units (MSDUs).and organizes them into MAC protocol
data units (MPDUs) for transmission over the air. For received transmissions, the MAC layer
does the reverse. . The MAC protocols may use either distributed multiple access techniques or
centrally coordinates the access for all devices, or even uses a combination of two.
The IEEE 802.16 MAC protocol was designed for point-to-multipoint (PMP) broadband wireless
access application, and is based on collision sense multiple access with collision avoidance
(CSMA/CA). But to accommodate the more demanding physical environment and different
service requirements MAC supports mesh, rather than only point to multipoint network
architectures. The IEEE 802.16-2004 and IEEE 802.16e-2005 MAC design includes a
convergence sublayer that can interface with a variety of higher-layer protocols, such as ATM
TDM Voice, Ethernet, IP, and any unknown future protocol. IEEE 802.16 standard is designed to
work with outdoor networks, both in urban as well as rural areas. The MAC incorporates several
features suitable for a broad range of applications at different mobility rates, such as, privacy key
management (PKM) for MAC layer security; broadcast and multicast support; Manageability
primitives; high-speed handover and mobility management primitives; three power management
levels, normal operation, sleep and idle; Header suppression, packing and fragmentation for
efficient use of spectrum. These features along with benefits scalable OFDMA make 802.16
suitable for high-speed data and bursty or isochronous IP multimedia applications.
The IEEE 802.16 MAC layer is composed of three sub-layers: Service Specific Convergence
Sub-layer (CS); MAC Common Part Sub-layer (CPS); and the Security Sub-layer. Each sub-layer
has a specific function to perform.
IEEE 802.16 MAC LAYER
8. 514 Computer Science & Information Technology ( CS & IT )
The Service-Specific Convergence Sub-layer (CS) provides any transformation or mapping of
external network data, received through the CS service access point (SAP), into MAC SDUs
received by the MAC Common Part Sub-layer (CPS) through the MAC SAP.
The core part of the IEEE 802.16 MAC is the MAC CPS, as it provides the core MAC
functionality of system access, bandwidth allocation, connection establishment, and connection
maintenance. Also functions like uplink scheduling, bandwidth request and grant, connection
control, and automatic repeat request (ARQ) are also defined. Communication between the CS
(Convergence Sub-layer) and the MAC CPS are maintained by MAC Service Access Point (MAC
SAP).The four basic actions of communication that is creation of connection, modification of
connection, deletion of connection and transport of data over the connection is done at this layer.
The MAC also contains a separate security sublayer providing authentication, secure key
exchange, and encryption. Data, PHY control, and statistics are transferred between the MAC
CPS and the PHY via the PHY SAP (which is implementation specific).
3.1 Quality of Service (QoS) Service classes:
QoS or Quality of Service is a key element in the delivery of service over the IEEE 802.16
medium. IEEE 802.16 defines five QoS service classes:
Unsolicited Grant Scheme (UGS), Extended Real Time Polling Service (ertPS), Real Time
Polling Service (rtPS), Non Real Time Polling Service (nrtPS), and Best Effort Service (BE).
Each of these has its own QoS parameters such as minimum throughput requirement and
delay/jitter constraints.
Comparison of QoS Classes
UGS: This class is used for real time services such as VoIP or for other application where
WiMAX is used for fixed lines replacement.
rtPS: This class is also used for real time services including video streaming. It is also used for
enterprise access services. This class offers variable bit rate but with guaranteed minimums for
data rate and delay.
9. Computer Science & Information Technology ( CS & IT ) 515
ertPS: This class is used for applications where variable packet sizes are used. E.g. Skype
nrtPS: This class is used for services where a guaranteed bit rate is required but the latency is not
critical. It might be used for various forms of file transfer.
BE: This class is used for internet services such as email and browsing. Data packets are carried
as space become available.
However, for non-real-time traffic, traffic priority is also one the QoS parameters that can
differentiate among different connections or subscribers within the same service class.
3.2 Scheduler:
Scheduling is the chief feature of the MAC layer that helps assure variable QoS. The Scheduler
works as distributor of allocated resources to mobile stations (MS). The allocated resource can be
defined as the number of slots and then these slots are mapped into a number of subchannels
(each subchannel is a group of multiple physical subcarriers) and time duration (OFDM symbols).
The mapping process from logical subchannel to multiple physical subcarriers is called a
permutation. Partial Used
Subchannelization (PUSC), Fully Used Subchannelization (FUSC), Adaptive Modulation and
Coding (band-AMC) are different permutation modes. The term band-AMC distinguishes the
permutation from adaptive modulation and coding (AMC) MCS selection procedure. Basically
there are two types of permutations: distributed and adjacent. The distributed subcarrier
permutation is suitable for mobile users while adjacent permutation is for fixed (stationary) users.
The Scheduler logically assigns the resources in terms of number of slots, it decides the
assignment of sub carrier allocation. . In systems with Single Carrier PHY, the scheduler assigns
the entire frequency channel to a MS, also deciding how to allocate the number of slots in a frame
for each user.
In systems with OFDM PHY, the scheduler considers the modulation schemes for various
subcarriers and decides the number of slots allocated. In systems with OFDMA PHY, the
scheduler needs to take into consideration the fact that a subset of subcarriers is assigned to each
user. Physically the scheduler decides which subchannels and time intervals are suitable for
different users. The goal is to minimize power consumption, to minimize bit error rate and to
maximize the total throughput.
3.3 Hybrid Automatic Repeat Request (HARQ):
HARQ or Hybrid Automatic Repeat Request is a system used by 802.16m to ensure all packets
are transmitted and correctly received. In this system, each frame is sent; the sender waits until it
received an ACK (acknowledgement) before sending the next frame. Multiple HARQ channels
can run in parallel (up to 16), mitigating the performance hit of waiting for an ACK before
sending more data.
IEEE 802.16e used a different version of HARQ, which is supported in 802.16m. The old version
is called Chain Combining, where exactly the same data is retransmitted when an ACK is not
received.802.16m uses a different variation of HARQ known as Incremental Redundancy, where
data is retransmitted with different encoding.
10. 516 Computer Science & Information Technology ( CS & IT )
4. IMT-ADVANCED FEATURES UNDER 802.16M (WiMAX rel 2.0
Systems):
4.1 Relays:
Intelligent relays are an effective technology to provide cost effective methods of delivering high
data rate and avoid coverage holes in deployments areas. In addition, upgrading the networks in
order to support higher data rates is equivalent to an increase of signal-to-interference plus noise
ratio (SINR) at the receivers’ front-end.
Relay stations are capable of decoding and forwarding the signals from source to destination
through radio interface. Relay stations do not need a wire backhaul. The system performance can
be further improved by intelligent resource scheduling and cooperative transmissions in systems
employing intelligent relays.
Implementation of relays
Two different relay modes are defined in this standard, transparent mode and Non- transparent
mode.
The transparent relay mode increases the throughput which facilities capacity increases within the
Base Station (BS) coverage area. It has no support to coverage extension because it does not
forward framing information to BS. It is operated in two hop network topology and supports
centralized scheduling only as scheduling is done only in BS.
The Non transparent relay mode is to increase the coverage extension of BS, here Relay Stations
(RS) generate its own framing information and forward it to Mobile Station (MS). It operates is 2
or more hops and uses centralized or distributed scheduling mode, as scheduling is done in BS
and RSs.
4.2 Femtocell and Self Organizing Networks:
Femtocells in 802.16m are low powered access points, to provide access to closed or open group
of users as configures by the subscribers. Femtocells are normally connected to service provider’s
11. Computer Science & Information Technology ( CS & IT ) 517
network. For femtocells base stations which can support relay links, it may establish air interface
connection with overlapping macrocell base station for exchange of control message.
Femtocell BS is intended to serve public users, like public WiFi hot spot, or to serve closed
subscriber group (CSG) that is a set of subscribers authorized by the femtocell BS owner or the
service provider. CSG can be modified by the service level agreement between the subscriber and
the access provider.
Femtocells working principle
Femtocells coupled with feature of self organizing systems, coverage and capacity optimization,
software upgradations and handover optimization are supported in 802.16m to maximize overall
network parameters. The scope of self organizing networks in 802.16m is limited to the
measurement and reporting of air interface performance metrics, and the subsequent adjustments.
Self Organization can be divided into two:
• Initializing and configuring Base Stations automatically with minimum human
• Self-optimization from the BS/MS and fine tuning the BS parameters in order to optimize
the network performance which includes QoS, network efficiency, throughput, cell
coverage and cell capacity.
4.3 Backward Compatibility and coexistence:
IEEE 802.16m base stations will support interoperability with 802.16e systems. An IEEE
802.16m mobile station will operate with 802.16e at performance similar 802.16 mobile station.
An 802.16m capable bas station will support interworking with 802.16 m and 802.16e devices.
4.4 Multi Carrier Aggregation:
Flexible spectrum use is achieved through use of scalable OFDMA multiple access scheme,
(Scalable OFDMA is a version of OFDMA in which the sub carrier spacing is independent of
bandwidth and the number of subcarriers scales with bandwidth) in the DL and UL tone dropping
12. 518 Computer Science & Information Technology ( CS & IT )
techniques in OFDMA, as well as use of one of multiple RF carriers. Multiple component carriers
can be aggregated upto to 100 MHZ transmission bandwidth. The aggregated component carriers
can be either contiguous or non-contiguous in the frequency domain. Channel bandwidth of 5, 10,
20 and 40(optional) is supported in 16m with multi carrier aggregation up to 100 MHZ.
4. CONCLUSION
This paper gives an overview of the PHY and MAC layer specifications of the IEEE 802.16m
standard also known as WiMAX Rel. 2.0. It gives various other details on the IEEE 802.16 m
standard which are in accordance of the IMT-Advanced specifications, given by the ITU. With
the IEEE 802.16m update the WiMAX mobile technology is expected to be a candidate for 4G
systems, as it meets the specifications under IMT-Advanced. For high bandwidth demand of the
future wireless networks IEEE 802.16m is a strong candidate, expected to provide data rates in
the range of 1 Gbps for high speed mobile users.
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