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.
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.
Secure and Service-Oriented Network Control Framework for WiMAX Networks
IEEE 802.16 supports both TDD ( time-division duplex) and FDD (frequency-division duplex)
Multihop communication is needed for deployment of wimax network. Because of multihop
Security is issues associated with wimax network
Issue is how to support different services and applications in WiMAX networks
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This paper gives an introduction on the IEEE 802.16 standard – WIMAX or Worldwide Interoperability for
Microwave Access. The different parts give details on the architectural specifications of WiMAX networks
and also on the working principle of WiMAX networks including its services provided. It also provides brief
descriptions on its salient features of this technology and how it benefits the networking industry. A brief
outline of the basic building blocks or equipment of WiMAX architecture is also provided. This paper also
evaluates the simulation performance of IEEE 802.16 OFDM PHY layer. The Stanford University Interim
(SUI) channel model under varying parameters is selected for the wireless channel in the simulation. The
performance measurements and analysis was done in simulation developed in MATLAB.
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.
Secure and Service-Oriented Network Control Framework for WiMAX Networks
IEEE 802.16 supports both TDD ( time-division duplex) and FDD (frequency-division duplex)
Multihop communication is needed for deployment of wimax network. Because of multihop
Security is issues associated with wimax network
Issue is how to support different services and applications in WiMAX networks
BER PERFORMANCE ANALYSIS FOR WIMAX PHY LAYER UNDER DIFFERENT CHANNEL CONDITIONSijistjournal
This paper gives an introduction on the IEEE 802.16 standard – WIMAX or Worldwide Interoperability for
Microwave Access. The different parts give details on the architectural specifications of WiMAX networks
and also on the working principle of WiMAX networks including its services provided. It also provides brief
descriptions on its salient features of this technology and how it benefits the networking industry. A brief
outline of the basic building blocks or equipment of WiMAX architecture is also provided. This paper also
evaluates the simulation performance of IEEE 802.16 OFDM PHY layer. The Stanford University Interim
(SUI) channel model under varying parameters is selected for the wireless channel in the simulation. The
performance measurements and analysis was done in simulation developed in MATLAB.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
A MAC PROTOCOL WITH DYNAMIC ALLOCATION OF TIME SLOTS BASED ON TRAFFIC PRIORIT...ijaia
In a wireless body area network (WBAN), wireless biomedical sensors are placed around, on, or inside the human body. Given specific requirements, WBANs can significantly improve healthcare, diagnostic monitoring, and other medical services. However, the existing standards such as IEEE 802.11 and IEEE 802.15.4 have some limitations to meet all the requirements of WBANs. Many medium access control (MAC) protocols have been studied so far, most of which are derived from the IEEE 802.15.4 superframe structure with some improvements and adjustments. However, the MAC protocols do not provide the required quality of service (QoS) for various types of traffic in a WBAN. In this paper, a traffic-aware MAC (TA-MAC) protocol for WBANs is proposed, in which time slots are dynamically allocated on the basis of traffic priority, providing the required QoS. According to the performance evaluation results, the proposed TA-MAC is better than IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of transmission time, system throughput, energy efficiency, and collision ratio.
Handover Behaviour of Transparent Relay in WiMAX NetworksIDES Editor
The knowledge on handover behaviour in WiMAX
network is essential for network management and planning
in order to achieve optimum system throughput. In this paper
we have analysed the handover behaviour of transparent relay
in several configurations for the IEEE 802.16j Mobile Multihop
Relay (MMR) WiMAX network. The simulation was
performed using NCTUns tool and adopted the hard handover
mechanism for three different relay network topologies with
varying mobile station speeds. The result shows the handover
for internal network is faster than the external network and
by appropriate relay deployment the system throughput can
be increased up to 14.39%.
WiMAX Features, Characteristics and Application in Wireless Technology Computingijtsrd
WiMAX stands for Worldwide Interoperability for Microwave Access which is also called as IEEE 802.16, the WiMAX technology is basically a wireless broadband communications technology, and it is used to provide higher data rate with increased coverage area. It means that it is based on IEEE 802.16 standard, which provides high speed data over a wide area. This technology can operate Non LOS non line of site . WiMAX is considered as a technology for point to multipoint wireless networking. In this paper it cover about WiMAX, WiMAX feature, it's Characteristics and Application and their architecture of WiMAX. Khushboo Kumari ""WiMAX Features, Characteristics and Application in Wireless Technology Computing"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-2 , February 2020,
URL: https://www.ijtsrd.com/papers/ijtsrd30204.pdf
Paper Url : https://www.ijtsrd.com/computer-science/computer-network/30204/wimax-features-characteristics-and-application-in-wireless-technology-computing/khushboo-kumari
Performance of Vehicle-to-Vehicle Communication using IEEE 802.11p in Vehicul...IJNSA Journal
Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the ITS environment. Many of these applications require real-time communication with high reliability. To meet a real-time deadline, timely and predictable access to the channel is paramount. The medium access method used in 802.11p, CSMA with collision avoidance, does not guarantee channel
access before a finite deadline. The well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets because no channel access was possible before the next message was generated. To overcome this problem, we propose to use STDMA for real-time data traffic between vehicles. The realtime properties of STDMA are investigated by means of the highway road simulation scenario, with promising results.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
An Investigation on Standards and Applications of Signalling System No.7IJRES Journal
Signaling system 7 (SS7) is the standard communication system that has been used to control public telephone networks since 1980s. Also to control the GSM network (for related and not related circuit signal), SS7 technology later offers advanced intelligent network features.SS7 network are now interconnecting with and operating on Internet data network (SS7 over IP). Based on signaling system- No.7 , a device named REMOTE CONTROL OBSERVER has been developed. The purpose of this device is to start, switch off, open, lock, break down and display the location of the vehicle on the electronic map which is fixed inside it; also it enables the Security Department to locate the place and direction of vehicle inside the GSM Network. The device is consists of a screen (displays the electronic map), and a box consists of a device similar to the cellular phone (with few differences ) , batteries and electronic circuit used to break down the electrical circuit of the vehicle ,where the device is subscribed with the GSM Network. The main advantage of this device is to use the available technologies and applications with adding and amending some of the programs and tasks for cellular phone and using the data base of the Home Location Register (HLR) and Visitor Location Register (VLR) by connecting a terminal to enable the user to search for any vehicle.
LINK-LEVEL PERFORMANCE EVALUATION OF RELAY-BASED WIMAX NETWORKijwmn
Relay technology promises appreciable network throughput and coverage enhancement which is required
for high speed wireless cellular systems to function to their optimum. This paper is focused on analysing
the link performance of a relay-based WiMAX network under varying conditions. Comparison is made
between relay and direct link communication in terms of BER (Bit Error Rate), spectral efficiency and
capacity. Effect of multipath fading and user speed on performance are investigated as well. The entire
study involves a hypothetical view as well as MATLAB simulations to predict the benefit of relay
deployment. This is aimed at solving pertinent issues such as coverage holes and cell edge problems which
are associated with traditional non-relay based cellular networks.
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Tight Coupling Internetworking Between UMTS and WLAN: Challenges, Design Arch...CSCJournals
To provide seamless internet connectivity anywhere at any time to the mobile users, there is a strong demand for the integration of wireless access networks for all-IP based Next Generation Networks (NGN). The Wireless Local Area Network (WLAN) is capable of providing high data rate at low cost. However, its services are limited to a small geographical area. Universal Mobile Telecommunications System (UMTS) networks provide global coverage, however, cost is high and the provided data rate do not fulfill the requirements of bandwidth intensive applications. By integrating these two promising technologies; UMTS and WLAN several benefits can be achieved, i.e., load balancing, extension of coverage area, better Quality of Service (QoS), improved security features, etc. Therefore, the integration of these two technologies can provide ubiquitous connectivity and high data rate at low cost to wireless clients. In this paper different integration mechanisms of UMTS and WLAN are investigated. More precisely, an integrated mechanism for the integration of UMTS and WLAN based on two different variations of tight coupling, i.e., interconnecting WLAN with Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) is designed and analyzed. The simulated results reveal that the GGSN-WLAN integration performance is better than the SGSN-WLAN integration for all the applied applications and measurement parameters.
Multi-layer heterogeneous network layout including small cell base stations are considered to be the key to further enhancements of the spectral efficiency achieved in mobile communication networks. It has been recognized that inter-cell interference has become the limiting factor when trying to achieve not only high average user satisfaction, but a high degree of satisfaction for as many users as possible. Therefore, inter-cell interference coordination (ICIC) lies in the focus of researchers defining next generation mobile communication standards, such as LTE-A.
Building upon [1], this paper provides an overview over the background calling for ICIC in heterogeneous LTE-A networks. It outlines techniques standardized in Rel. 10 of LTE-A, discusses them showing their benefits and limitations by means of system-level simulations and motivates the importance of self optimizing network (SON) procedures for ICIC in LTE-A.
Abstract: A quality of service framework is a fundamental component of a 4G broadband wireless network for satisfactory service delivery of evolving Internet applications to end users, and managing the network resources. Today’s popular mobile Internet applications, such as voice, gaming, streaming, and social networking services, have diverse traffic characteristics and, consequently, different QoS requirements. A rather flexible QoS framework is highly desirable to be future-proof to deliver the incumbent as well as emerging mobile Internet applications. This article highlights QoS frameworks and features of OFDMA-based 4G technologies — IEEE 802.16e, IEEE 802.16m — to support various applications’ QoS requirements. A few advanced QoS features such as new scheduling service (i.e., aGP), quick access, delayed bandwidth request, and priority controlled access in IEEE 802.16m are explained in detail. A brief comparison of the QoS framework of the aforementioned technologies is also provide
Next Generation 4G WiMAX Networks - IEEE 802.16 Standard: cscpconf
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.
The relay stations are widely used in major wireless technologies such as WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long term evolution) which provide cost effective service to the operators and end users. It is quite challenging to provide guaranteed Quality of Service (QoS) in WiMAX networks in cost effective manner.
COMPARATIVE PERFORMANCE ANALYSIS OF THE IEEE802.11AX AND 802.11AC MIMOLINK FO...pijans
The escalating demand for swift and dependable wireless internet access has spurred the development of
various protocols within 802.11 WLANs. Among them, the 802.11ac protocols have gained widespread
acceptance over the past few years, offering enhanced data transfer rates compared to the 802.11n
standard. However, the persistent congestion of wireless IoT devices, particularly in densely populated
areas, remains a significant challenge. To tackle this issue, IEEE 802.11 has advanced IEEE 802.11ax as
the successor to 802.11ac, introducing critical enhancements at the PHY/MAC layers to improve
throughput in dense scenarios. Additionally, modelling and simulating these protocols are vital for WLAN
researchers and designers to anticipate link characteristics effectively, fostering high-performance WLAN
design. The need for such tools led to the creation of diverse network simulation programs, and NS-2 is
widely accepted as an open-source program that has achieved remarkable success in research. In this
paper, we focus on various connection properties of 802.11ax WLANs through NS-3 simulations, including
MCSs, bonded channels, GI, data encoding, antennas, data rates, link distance, Tx/Rx power, gain, and
payload size. We also compare their performance against 802.11ac, which demonstrates that NS-3
accurately supports most 802.11ax capabilities and outperforms 802.11ac in various scenarios.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
A MAC PROTOCOL WITH DYNAMIC ALLOCATION OF TIME SLOTS BASED ON TRAFFIC PRIORIT...ijaia
In a wireless body area network (WBAN), wireless biomedical sensors are placed around, on, or inside the human body. Given specific requirements, WBANs can significantly improve healthcare, diagnostic monitoring, and other medical services. However, the existing standards such as IEEE 802.11 and IEEE 802.15.4 have some limitations to meet all the requirements of WBANs. Many medium access control (MAC) protocols have been studied so far, most of which are derived from the IEEE 802.15.4 superframe structure with some improvements and adjustments. However, the MAC protocols do not provide the required quality of service (QoS) for various types of traffic in a WBAN. In this paper, a traffic-aware MAC (TA-MAC) protocol for WBANs is proposed, in which time slots are dynamically allocated on the basis of traffic priority, providing the required QoS. According to the performance evaluation results, the proposed TA-MAC is better than IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of transmission time, system throughput, energy efficiency, and collision ratio.
Handover Behaviour of Transparent Relay in WiMAX NetworksIDES Editor
The knowledge on handover behaviour in WiMAX
network is essential for network management and planning
in order to achieve optimum system throughput. In this paper
we have analysed the handover behaviour of transparent relay
in several configurations for the IEEE 802.16j Mobile Multihop
Relay (MMR) WiMAX network. The simulation was
performed using NCTUns tool and adopted the hard handover
mechanism for three different relay network topologies with
varying mobile station speeds. The result shows the handover
for internal network is faster than the external network and
by appropriate relay deployment the system throughput can
be increased up to 14.39%.
WiMAX Features, Characteristics and Application in Wireless Technology Computingijtsrd
WiMAX stands for Worldwide Interoperability for Microwave Access which is also called as IEEE 802.16, the WiMAX technology is basically a wireless broadband communications technology, and it is used to provide higher data rate with increased coverage area. It means that it is based on IEEE 802.16 standard, which provides high speed data over a wide area. This technology can operate Non LOS non line of site . WiMAX is considered as a technology for point to multipoint wireless networking. In this paper it cover about WiMAX, WiMAX feature, it's Characteristics and Application and their architecture of WiMAX. Khushboo Kumari ""WiMAX Features, Characteristics and Application in Wireless Technology Computing"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-2 , February 2020,
URL: https://www.ijtsrd.com/papers/ijtsrd30204.pdf
Paper Url : https://www.ijtsrd.com/computer-science/computer-network/30204/wimax-features-characteristics-and-application-in-wireless-technology-computing/khushboo-kumari
Performance of Vehicle-to-Vehicle Communication using IEEE 802.11p in Vehicul...IJNSA Journal
Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the ITS environment. Many of these applications require real-time communication with high reliability. To meet a real-time deadline, timely and predictable access to the channel is paramount. The medium access method used in 802.11p, CSMA with collision avoidance, does not guarantee channel
access before a finite deadline. The well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets because no channel access was possible before the next message was generated. To overcome this problem, we propose to use STDMA for real-time data traffic between vehicles. The realtime properties of STDMA are investigated by means of the highway road simulation scenario, with promising results.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
An Investigation on Standards and Applications of Signalling System No.7IJRES Journal
Signaling system 7 (SS7) is the standard communication system that has been used to control public telephone networks since 1980s. Also to control the GSM network (for related and not related circuit signal), SS7 technology later offers advanced intelligent network features.SS7 network are now interconnecting with and operating on Internet data network (SS7 over IP). Based on signaling system- No.7 , a device named REMOTE CONTROL OBSERVER has been developed. The purpose of this device is to start, switch off, open, lock, break down and display the location of the vehicle on the electronic map which is fixed inside it; also it enables the Security Department to locate the place and direction of vehicle inside the GSM Network. The device is consists of a screen (displays the electronic map), and a box consists of a device similar to the cellular phone (with few differences ) , batteries and electronic circuit used to break down the electrical circuit of the vehicle ,where the device is subscribed with the GSM Network. The main advantage of this device is to use the available technologies and applications with adding and amending some of the programs and tasks for cellular phone and using the data base of the Home Location Register (HLR) and Visitor Location Register (VLR) by connecting a terminal to enable the user to search for any vehicle.
LINK-LEVEL PERFORMANCE EVALUATION OF RELAY-BASED WIMAX NETWORKijwmn
Relay technology promises appreciable network throughput and coverage enhancement which is required
for high speed wireless cellular systems to function to their optimum. This paper is focused on analysing
the link performance of a relay-based WiMAX network under varying conditions. Comparison is made
between relay and direct link communication in terms of BER (Bit Error Rate), spectral efficiency and
capacity. Effect of multipath fading and user speed on performance are investigated as well. The entire
study involves a hypothetical view as well as MATLAB simulations to predict the benefit of relay
deployment. This is aimed at solving pertinent issues such as coverage holes and cell edge problems which
are associated with traditional non-relay based cellular networks.
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Tight Coupling Internetworking Between UMTS and WLAN: Challenges, Design Arch...CSCJournals
To provide seamless internet connectivity anywhere at any time to the mobile users, there is a strong demand for the integration of wireless access networks for all-IP based Next Generation Networks (NGN). The Wireless Local Area Network (WLAN) is capable of providing high data rate at low cost. However, its services are limited to a small geographical area. Universal Mobile Telecommunications System (UMTS) networks provide global coverage, however, cost is high and the provided data rate do not fulfill the requirements of bandwidth intensive applications. By integrating these two promising technologies; UMTS and WLAN several benefits can be achieved, i.e., load balancing, extension of coverage area, better Quality of Service (QoS), improved security features, etc. Therefore, the integration of these two technologies can provide ubiquitous connectivity and high data rate at low cost to wireless clients. In this paper different integration mechanisms of UMTS and WLAN are investigated. More precisely, an integrated mechanism for the integration of UMTS and WLAN based on two different variations of tight coupling, i.e., interconnecting WLAN with Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) is designed and analyzed. The simulated results reveal that the GGSN-WLAN integration performance is better than the SGSN-WLAN integration for all the applied applications and measurement parameters.
Multi-layer heterogeneous network layout including small cell base stations are considered to be the key to further enhancements of the spectral efficiency achieved in mobile communication networks. It has been recognized that inter-cell interference has become the limiting factor when trying to achieve not only high average user satisfaction, but a high degree of satisfaction for as many users as possible. Therefore, inter-cell interference coordination (ICIC) lies in the focus of researchers defining next generation mobile communication standards, such as LTE-A.
Building upon [1], this paper provides an overview over the background calling for ICIC in heterogeneous LTE-A networks. It outlines techniques standardized in Rel. 10 of LTE-A, discusses them showing their benefits and limitations by means of system-level simulations and motivates the importance of self optimizing network (SON) procedures for ICIC in LTE-A.
Abstract: A quality of service framework is a fundamental component of a 4G broadband wireless network for satisfactory service delivery of evolving Internet applications to end users, and managing the network resources. Today’s popular mobile Internet applications, such as voice, gaming, streaming, and social networking services, have diverse traffic characteristics and, consequently, different QoS requirements. A rather flexible QoS framework is highly desirable to be future-proof to deliver the incumbent as well as emerging mobile Internet applications. This article highlights QoS frameworks and features of OFDMA-based 4G technologies — IEEE 802.16e, IEEE 802.16m — to support various applications’ QoS requirements. A few advanced QoS features such as new scheduling service (i.e., aGP), quick access, delayed bandwidth request, and priority controlled access in IEEE 802.16m are explained in detail. A brief comparison of the QoS framework of the aforementioned technologies is also provide
Next Generation 4G WiMAX Networks - IEEE 802.16 Standard: cscpconf
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.
The relay stations are widely used in major wireless technologies such as WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long term evolution) which provide cost effective service to the operators and end users. It is quite challenging to provide guaranteed Quality of Service (QoS) in WiMAX networks in cost effective manner.
COMPARATIVE PERFORMANCE ANALYSIS OF THE IEEE802.11AX AND 802.11AC MIMOLINK FO...pijans
The escalating demand for swift and dependable wireless internet access has spurred the development of
various protocols within 802.11 WLANs. Among them, the 802.11ac protocols have gained widespread
acceptance over the past few years, offering enhanced data transfer rates compared to the 802.11n
standard. However, the persistent congestion of wireless IoT devices, particularly in densely populated
areas, remains a significant challenge. To tackle this issue, IEEE 802.11 has advanced IEEE 802.11ax as
the successor to 802.11ac, introducing critical enhancements at the PHY/MAC layers to improve
throughput in dense scenarios. Additionally, modelling and simulating these protocols are vital for WLAN
researchers and designers to anticipate link characteristics effectively, fostering high-performance WLAN
design. The need for such tools led to the creation of diverse network simulation programs, and NS-2 is
widely accepted as an open-source program that has achieved remarkable success in research. In this
paper, we focus on various connection properties of 802.11ax WLANs through NS-3 simulations, including
MCSs, bonded channels, GI, data encoding, antennas, data rates, link distance, Tx/Rx power, gain, and
payload size. We also compare their performance against 802.11ac, which demonstrates that NS-3
accurately supports most 802.11ax capabilities and outperforms 802.11ac in various scenarios.
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.
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.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
IEEE 802.11n Based Wireless Backhaul Enabled by Dual Channel IPT (DCH-IPT) Fo...CSCJournals
Wireless backhaul has received much attention as an enabler of future broadband mobile communication systems because it can reduce deployment cost of pico-cells, an essential part of high capacity system. A high throughput with a minimum delay network is highly appreciated to sustain the increasing proliferation in multimedia transmissions. In this paper, we propose a backhaul network using the Multi-Input Multi-Output (MIMO) IEEE 802.11n standard in conjunction with the Dual Channel Intermittent Periodic Transmit IPT (DCH-IPT) packets forwarding protocol. By using these two techniques (IEEE 802.11n + DCH-IPT), wireless backhaul nodes can meet more demanding communication requirements such as higher throughput, lower average delay, and lower packet dropping rate than those achieved by the currently used backhaul. The current backhaul is based upon Single-Input Single-Output (SISO) IEEE 802.11a,b,g standards in conjunction with Single Channel Conventional (SCH-Conv) relaying protocol in which packets are transmitted continuously from source nodes using single channel. The proposed backhaul will accelerate introduction of picocell based mobile communication systems.
An Efficient Wireless Backhaul Utilizing MIMO Transmission and IPT ForwardingCSCJournals
Wireless backhaul has been received much attention as an enabler of future broadband mobile communication systems because it can reduce deployment cost of pico-cells, an essential part of high capacity system. A high performance network, high throughput, low average delay and low packet loss rate, is highly appreciated to sustain the increasing proliferation in multimedia transmissions. The critical issue reducing the performance of wireless backhaul is the interference occurred in the network due to simultaneous nodes transmissions. In this research, we propose a high performance wireless backhaul using the low interference sensitivity MIMO based nodes. MIMO transmission has a better BER performance over SISO one even with the same transmission rate and bandwidth, which means that MIMO can operate at lower SINR values than SISO and give the same performance. This MIMO robust performance against interference gives us a greater benefit when adopted as a wireless interface in wireless backhaul than SISO. These facts motivated us to use the IEEE 802.11n the current MIMO standard to design a MIMO based wireless backhaul. In addition and to justify our assumptions, we investigate the effect of MIMO channels correlation, a major drawback in MIMO transmission, upon the system performance, and prove the robustness of the scheme under different MIMO channels correlation values. After proving the effectiveness of MIMO as a wireless interface for wireless backhaul, we further improve the performance of this MIMO-backhaul using the high efficient Intermittent Periodic Transmit (IPT) forwarding protocol. IPT is a reduced interference packet forwarding protocol with a more efficient relay performance than conventional method in which packets are transmitted continuously form the source nodes. By using these two techniques (IEEE 802.11n (MIMO) + IPT), wireless backhaul nodes can meet more demanding communication requirements such as higher throughput, lower average delay, and lower packet dropping rate than those achieved by simply applying IEEE 802.11n to conventionally relayed backhaul. The proposed wireless backhaul will accelerate introduction of picocell based mobile communication systems.
Analysis of wifi and wimax and wireless network coexistenceIJCNCJournal
Wireless networks are very popular nowadays. Wireless Local Area Network (WLAN) that uses the IEEE 802.11 standard and WiMAX (Worldwide Interoperability for Microwave Access) that uses the IEEE802.16 standard are networks that we want to explore. WiMAX has been developed over 10 years, but it is still unknown by most people. However, compared with WLAN, it has many advantages in transmission speed and coverage area. This paper will introduce these two technologies and make comparisons between WiMAX and WiFi. In addition, wireless network coexistence of WLAN and WiMAX will be explored through simulation. Lastly we want to discuss the future of WiMAX in relation to WiFi.
This paper presents a comparative study of IEEE 802.11 a/b/g/n wireless LAN standards in an ELearning classroom network using adhoc networks as communication support. The evaluation is performed through a series of scenarios schematizing communication between students and practitioners in an educational context. The first objective is to plan the physical layer via the choice of the suitable transmission standard that satisfy the implementation specifications. Given the real-time traffic considered, a good traffic transmission must be ensured.
ESTIMATION AND COMPENSATION OF INTER CARRIER INTERFERENCE IN WIMAX PHYSICAL L...ijngnjournal
WiMAX is Wireless Interoperability for Microwave Access has emerged as a promising solution for transmission of higher data rates for fixed and mobile applications. IEEE 802.16d and e are the standards proposed by WiMAX group for fixed and mobile. As the wireless channel have so many limitation Such as Multipath, Doppler spread, Delay spread and Line Of Sight (LOS)/Non Line Of Sight (NLOS) components. To attain higher data rates the Multi Carrier System with Multiple Input and Multiple Output (MIMO) is incorporated in the WiMAX. The Orthogonal Frequency Division Multiplexing (OFDM) is a multi carrier technique used with the WiMAX systems. In OFDM the available spectrum is split into numerous narrow band channels of dissimilar frequencies to achieve high data rate in a multi path fading environment. And all these sub carriers are considered to be orthogonal to each other. As the number of sub carriers is increased there is no guarantee of sustained orthogonality, i.e. at some point the carriers are not
independent to each other, and hence where the orthogonality can be loosed which leads to interference and also owing to the synchronization between transmitter and receiver local oscillator, it causes interference known as Inter Carrier Interference (ICI). The systems uses MIMO-OFDM will suffer with the effects of ICI and Carrier Frequency Offset (CFO) “ε”. However these affect the power leakage in the midst of sub carriers, consequently degrading the system performance. In this paper a new approach is proposed in order to reduce the ICI caused in WiMAX and improve the system performance. In this scheme at the transmitter side the modulated data and a few predefined pilot symbols are mapped onto the non
neighboring sub carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols the frequency offset is exactly estimated by using Maximum Likelihood Estimation (MLE) and hence can be minimized. At demodulation stage the received signals are linearly combined along with their weighted
coefficients and pilot symbols, called as Pilot Aided Self Cancellation Method (PASCS). And also to realize the various wireless environments the simulations are carried out on Stanford University Interim (SUI) channels. The simulation results shows that by incorporating this method into WiMAX systems it performs better when the Line Of Sight (LOS) component is present in the transmission and also it improves the Bit Error Rate (BER) and Carrier to Interference Ratio (CIR). The CIR can be improved 20 dB. In this paper the effectiveness of PASCS scheme is compared with the Self Cancellation Method (SCM). It provides accurate estimation of frequency offset and when residual CFO is less significant the ICI can be diminished successfully.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
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Francesca Gottschalk - How can education support child empowerment.pptx
Survey on mobile wimax
1. (IJCSIS) International Journal of Computer Science and Information Security,
Vol. 8, No. 1, April 2010
A Survey of Mobile WiMAX IEEE 802.16m
Standard.
Mr. Jha Rakesh
Deptt. Of E & T.C.
SVNIT
Surat, India
Jharakesh.45@gmail.com
Mr. Wankhede Vishal A.
Deptt. Of E & T.C.
SVNIT
Surat, India
wankhedeva@gmail.com
earlier this year has added mobility support. This is generally
referred to as mobile WiMAX [1].
Abstract— IEEE 802.16m amends the IEEE 802.16 Wireless
MAN-OFDMA specification to provide an advanced air
interface for operation in licenced bands. It will meet the
cellular layer requirements of IMT-Advanced next generation
mobile networks. It will be designed to provide significantly
improved performance compared to other high rate
broadband cellular network systems. For the next generation
mobile networks, it is important to consider increasing peak,
sustained data reates, corresponding spectral efficiencies,
system capacity and cell coverage as well as decreasing latency
and providing QoS while carefully considering overall system
complexity. In this paper we provide an overview of the stateof-the-art mobile WiMAX technology and its development. We
focus our discussion on Physical Layer, MAC Layer,
Schedular,QoS provisioning and mobile WiMAX specification.
Mobile WiMAX adds significant enhancements:
• It improves NLOS coverage by utilizing advanced
antenna diversity schemes and hybrid automatic repeat
request (HARQ).
• It adopts dense subchannelization, thus increasing
system gain and improving indoor penetration.
• It uses adaptive antenna system (AAS) and multiple
input multiple output (MIMO) technologies to improve
coverage [2].
• It introduces a downlink subchannelization scheme,
enabling better coverage and capacity trade-off [3-4].
Keywords-Mobile WiMAX; Physical Layer; MAC Layer;
Schedular; Scalable OFDM.
I.
Prof. Dr. Upena Dalal
Deptt. Of E & T.C.
SVNIT
Surat, India
upena_dalal@yahoo.com
This paper provides an overview of Mobile
WiMAX standards and highlights potential problems arising
from applications. Our main focuses are on the PHY layer,
MAC layer specifications of mobile WiMAX. We give an
overview of the MAC specification in the IEEE 802.16j and
IEEE802.16m standards, specifically focusing the discussion
on scheduling mechanisms and QoS provisioning. We
review the new features in mobile WiMAX, including
mobility support, handoff, and multicast services. We discuss
technical challenges in mobile WiMAX deployment. We
then conclude the paper.
INTRODUCTION
IEEE 802.16, a solution to broadband wireless
access (BWA) commonly known as Worldwide
Interoperability for Microwave Access (WiMAX), is a recent
wireless broadband standard that has promised high
bandwidth over long-range transmission. The standard
specifies the air interface, including the medium access
control (MAC) and physical (PHY) layers, of BWA. The key
development in the PHY layer includes orthogonal
frequency-division multiplexing (OFDM), in which multiple
access is achieved by assigning a subset of subcarriers to
each individual user [1]. This resembles code-division
multiple access (CDMA) spread spectrum in that it can
provide different quality of service (QoS) for each user; users
achieve different data rates by assigning different code
spreading factors or different numbers of spreading codes. In
an OFDM system, the data is divided into multiple parallel
substreams at a reduced data rate, and each is modulated and
transmitted on a separate orthogonal subcarrier. This
increases symbol duration and improves system robustness.
OFDM is achieved by providing multiplexing on user’s data
streams on both uplink and downlink transmissions.
II.
PHYSICAL LAYER OF IEEE 802.16M.
This section contains an overview of some Physical
Layer enhancements that are currently being considered for
inclusion in future systems. Because the development of the
802.16m standard is still in a relatively early stage, the focus
is on presenting the concepts and the principles on which the
proposed enhancements will be based, rather than on
providing specific implementation details. Although the
exact degree of sophistication of the new additions to the
standard cannot be safely predicted, it is expected that the
additions will make some use of the concepts described
below.
Lack of mobility support seems to be one of the major
hindrances to its deployment compared to other standards
such as IEEE 802.11 WLAN, since mobility support is
widely considered as one of the key features in wireless
networks. It is natural that the new IEEE 802.16e released
A.
Flexibility enhancements to support heterogeneous
users in IEEE 802.16m:
Because the goal of future wireless systems is to cater to
needs of different users, efficient and flexible designs are
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needed. For some users (such as streaming low-rate
applications) link reliability may be more important than
high data rates, whereas others may be interested in
achieving the maximum data rate even if a retransmission,
and, therefore, additional delay may be required [4-6].
Moreover, the co-existence of different users should be
achieved with relatively low control overhead. For these
reasons, the frame format, the subcarrier mapping schemes
and the pilot structure are being modified for 802.16m with
respect to 802.16e. Each 802.16e frame consists of a
downlink (DL) and an uplink (UL) part separated in time by
an OFDMA symbol and is of variable size [3,7]. The
(downlink or uplink) frame begins by control information
that all users employ to synchronize and to determine if and
when they should receive or transmit in the given frame.
Control information is followed by data transmission by the
base station (in the downlink subframe) or the mobile
stations (in the uplink subframe). For each mobile station,
transmission or reception happens in blocks that are
constructed from basic units called slots. Each slot can be
thought of as a two-dimensional block, one dimension being
the time, the other dimension being the frequency. In
general, a slot extends over one subchannel in the frequency
direction and over 1 to 3 OFDMA symbols in the time
direction, depending on the permutation scheme. The
subchannels are groups of OFDMA subcarriers. The number
of subcarriers per subchannel and the distribution of the
subcarriers that make up a subchannel in the OFDMA
symbol are determined based on the permutation scheme. As
explained in more detail below, the subcarriers of a given
subchannel are not always consecutive in frequency.
Downlink and uplink subframes can be divided into different
zones where different permutation schemes are used [9-10].
B.
Extending use of MIMO transmission
Multiple-Input Multiple-Output (MIMO) communication
is already a reality in wireless systems. It will be supported
by the IEEE 802.11n amendment to the 802.11 WLAN
standards that is expected to be ratified in the near future.
Similarly, 802.16e includes support for MIMO downlink and
uplink transmission. As MIMO technology matures and
implementation issues are being resolved, it is expected that
MIMO will be widely used for wireless communication.
Current Mobile WiMAX profiles include support for up to 2
transmit antennas even though the IEEE 802.16e standard
does not restrict the number of antennas, and allows up to 4
spatial streams. The current aim for Next Generation
WiMAX systems is to support at least up to 8 transmit
antennas at the base station, 4 streams and Space-Time
Coding [2]. 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.
In 802.11 systems, as well as in the 802.16e standard,
MIMO transmission is used to increase the data rate of the
communication between a given transmitter-receiver pair
and/or improve the reliability of the link. It is expected that
802.16m and future 3GPP systems will extend MIMO
support to Multi-user (MU-) MIMO. More specifically, use
of multiple antennas can improve the achievable rates of
users in a network with given frequency resources. In
information theoretic terms, the capacity region of the uplink
and the downlink increases, in general, when MIMO
transmission is employed [2]. In many cases, a large portion
of this capacity increase can be achieved using relatively
simple linear schemes (transmit beamforming at the
downlink and linear equalizers at the uplink). Therefore, the
achievable rates can be increased without the need for
sophisticated channel coding. If larger complexity can be
afforded, even higher gains can be attained using successive
decoding at the uplink and Dirty Paper Coding schemes at
the downlink. An overview of the projected MIMO
architecture for the downlink of 802.16m systems is given in
the System Description Document (SDD), and is repeated in
Fig. 1 for convenience.
In the Partial Usage of Subchannels (PUSC) zone that is
mandatory, the priority is to improve diversity and to spread
out the effect of inter-cell interference. Each slot extends
over 2 OFDMA symbols, and a subchannel consists of 24
data subcarriers that are distributed over the entire signal
bandwidth (OFDMA symbol). Thus, each subchannel has
approximately the same channel quality in terms of the
channel gain and the inter-cell interference. To reduce the
effect of the inter-cell interference, when PUSC is used, the
available subchannels are distributed among base stations so
that adjacent base stations not use the same subchannels.
When the inter-cell interference is not significant, as in the
case of mobile stations located closely to a base station, it
may be advantageous to employ Full Usage of Subchannels
(FUSC). The goal of the FUSC permutation scheme is
similar to PUSC, i.e, to improve diversity and to spread out
the effect of inter-cell interference. However, as the name
suggests, in the FUSC zone all subchannels are used by a
base station. For this reason, the design of the pilot pattern
for the FUSC zone is slightly more efficient compared to
PUSC. A subchannel in the FUSC permutation zone consists
of 48 data subcarriers and the slot only comprises one
OFDMA symbol.
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User1:data
Encoder
1.Resource
Mapping
Encoder
2. MIMO
Encoder
Sched
ular
IFFT
IFFT
Handover with other
technologies
Not Specified
IFFT
OFDM
Symbol
Constr-uction
Mobility Speed
Vehicular: 120 km/h
3.Beam
Precoder
Encoder
Precoding
Vector/
Matrix
Feedback
CSI
ACK/NAK
Mode/Link
Position accuracy
Figure 1. MIMO architecture for the downlink of 802.16m systems.
WiMAX and 3GPP networks employing MUMIMO will need to calculate which users should transmit
and receive during each frame, as well as the best
achievable rate that corresponds to each user based on their
QoS requirements, the number of users in each cell and their
position. Although the information-theoretic capacity has
been characterized, this is not an easy task, even for
narrowband systems, and it is even more challenging when
all subcarriers of the OFDMA system are considered.
Therefore, efficient algorithms will be needed at the base
station for user selection that will also determine the
beamforming filters for the downlink, the receiver filters for
the uplink and the required power allocation at the base
station and each mobile station.
C.
Resource allocation and multi-cell MIMO
In cellular networks careful frequency planning is
required in order to achieve communication with small
outage probability and, at the same time, minimize
interference among users of neighboring cells. Users near the
cell edges are particularly vulnerable, because they receive
signals of comparable strength from more than one base
stations [2]. For this reason, different parts of the frequency
spectrum are typically assigned to neighboring cells. The
assignment in current systems is static and can only be
changed by manual re-configuration of the system. Changes
to the frequency allocation can only be performed
periodically and careful cell planning is required in order not
to affect other parts of the system. Frequencies are reused by
cells that are sufficiently far away so that the interference
caused by transmissions on the same frequencies is small
enough to guarantee satisfactory Signal- to-Interference and
Noise Ratios (SINRs). Although static frequency reuse
schemes greatly simplify the design of cellular systems, they
incur loss in efficiency because parts of the spectrum in some
cells may remain unused while, at the same time, other cells
may be restricting the rates of their mobile stations or even
denying admission to new users. Moreover, the handover
process is more complicated for mobile stations since
communication in more than one frequencies is required.
TABLE I. MOST IMPORTANT FEATURES AND SYSTEM
REQUIREMENTS OF MOBILE WIMAX STANDARDS
Requirement
IEEE 802.16e
IEEE802.16m
Aggregate Data Rate
63 Mbps
100 Mbps for mobile
stations, 1 Gbps for
fixed
Operating
Frequency
2.3 GHz, 2.5-2.7
GHz, 3.5 GHz
< 6 GHz
Duplexing Schemes
TDD and FDD
TDD and FDD
MIMO support
up to 4 streams, no
limit on antennas
4 or 8 streams, no limit
on antennas
Coverage
10 km
3 km, 5-30 km and 30100 km
Handover
Interfrequency
Interruption Time
35-50 ms
depending on scenario
Not Specified
30 ms
From
802.16e
serving
BS
to
802.16e target BS
Not Specified
From legacy serving BS
to legacy target BS
From 802.16m serving
BS to legacy target BS
From legacy serving BS
to 802.16m target BS
From 802.16m serving
BS to 802.16m target
BS
IEEE 802.11, 3GPP2,
GSM/EDGE,
(E)UTRA (LTE TDD)
Using IEEE 802.21
Media
Independent
Handover (MIH)
Indoor: 10 km/h
Basic Coverage Urban:
120 km/h
High Speed: 350 km/h
Location Determination
Latency: 30 s
100 ms
Radio
Handover
Intrafrequency
Interruption Time
Handover
between
802.16 standards
(for
corresponding
mobile station)
D.
Interoperability and coexistence.
In order for the standard to be able to support either
legacy base and mobile stations or other technologies (e.g.
LTE), the concept of the time zone, an integer number
(greater than 0) of consecutive subframes, is introduced.
Interoperability among IEEE 802.16 standards [11]: The
802.16m Network Reference Model permits interoperability
of IEEE 802.16m Layer 1 and Layer 2 with legacy 802.16
standards. The motivation for ensuring interoperability
comes from the fact that WiMAX networks have already
been deployed, and it is more realistic to require
interoperability instead of an update of the entire network.
Another advantage is that each 802.16 standard provides
specific functionalities in a WiMAX network. The goal in
802.16m is to enable coexistence of all these functionalities
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units (SDUs) for the MAC CPS. This includes classification
of external data with the proper MAC service flow identifier
(SFID) and connection identifier (CID). An SDU is the basic
data unit exchanged between two adjacent protocol layers.
[11,14] The MAC CPS provides the core functionality for
system access, allocation of bandwidth, and connection
establishment and maintenance. This sublayer also handles
the QoS aspect of data transmission. The security sublayer
provides functionalities such as authentication, secure key
exchange, and encryption. For the PHY layer, the standard
supports multiple PHY specifications, each handling a
particular frequency range. The MAC CPS contains the
essential functionalities for scheduling and QoS provisioning
in the system.
in a network without the need to create a new standard that
contains all of them. The supported connections and frame
structure are summarized in Fig. 2 and Fig. 3. The legacy
standard can transmit during the legacy zones (also called
LZones), whereas 802.16m-capable stations can transmit
during the new zones. The Uplink (UL) portion shall start
with the legacy UL zone, because legacy base stations,
mobile stations or relays expect IEEE 802.16e UL control
information to be sent in this region. When no stations using
a legacy 802.16 standard are present, the corresponding zone
is removed. The zones are multiplexed using TDM in the
downlink, whereas both TDM and FDM can used in the
uplink. In each connection, the standard that is in charge is
showcased. The Access Service Network can be connected
with other network infrastructures (e.g. 802.11, 3GPP etc.) or
to the Connectivity Service Network in order to provide
Internet to the clients.
IEEE 802.16d MAC provides two modes of operation:
point-to-multipoint (PMP) and multipoint-to-multipoint
(mesh) [13]. The functionalities of the MAC sublayer are
related to PHY control (cross-layer functionalities, such as
HARQ ACK/NACK etc). The Control Signaling block is
responsible for allocating resources by exchanging messages
such as DL-MAP and UL-MAP. The QoS block allocates the
input traffic to different traffic classes based on the
scheduling and resource block, according to the SLA
guarantees. The name of other blocks, such as
fragmentation/packing,multi-radio coexistence and MAC
PDU formation, clearly describes their function. The MAC
sublayer also deploys state-of-the-art power saving and
handover mechanisms in order to enable mobility and make
connections available to speeds up to 350 km/h. Since newer
mobile devices tend to incorporate an increasing number of
functionalities, in WiMAX networks the power saving
implementation incorporates service differentiation on power
classes. A natural consequence of any sleeping mechanism is
the increase of the delay. Thus, delay-prone and non delayprone applications are allocated to different classes, such that
the energy savings be optimized, while satisfying the
appropriate QoS (e.g those that support web page
downloading or emails). MAC addresses play the role of
identification of individual stations. IEEE 802.16m
introduces two different types of addresses in the MAC
sublayer. 1) The IEEE 802 MAC address that has the generic
48-bit format and 2) two MAC logical addresses that are
assigned to the mobile station by management messages
from the base station. These addresses are used for resource
allocation and management of the mobile station and are
called “Station Identifiers” (assigned during network entry)
and “Flow Identifiers” (assigned for QoS purposes).
Figure 2. Supported 802.16 connections
Figure 3. IEEE 802.16m frame structure with TDM Downlink and FDM
Uplink
III.
BASIC FUNCTIONALITY OF MAC LAYER IN
WIMAX
Figure 4 presents the reference model in IEEE 802.16.
The MAC layer consists of three sublayers: the servicespecific convergence sublayer (CS), MAC common part
sublayer (MAC CPS), and security sublayer. The main
functionality of the CS is to transform or map external data
from the upper layers into appropriate MAC service data
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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. Scheduler designers
need to consider the allocations logically and physically.
Logically, the scheduler should calculate the number of slots
based on QoS service classes. Physically, the scheduler
needs to select which subchannels and time intervals are
suitable for each user. The goal is to minimize power
consumption, to minimize bit error rate and to maximize the
total throughput. There are three distinct scheduling
processes: two at the BS - one for downlink and the other for
uplink and one at the MS for uplink as shown in Fig. 5. At
the BS, packets from the upper layer are put into different
queues, which ideally is per-CID queue in order to prevent
head of line (HOL) blocking. However, the optimization of
queue can be done and the number of required queues can be
reduced. Then, based on the QoS parameters and some extra
information such as the channel state condition, the DL-BS
scheduler decides which queue to service and how many
service data units (SDUs) should be transmitted to the MSs.
Since the BS controls the access to the medium, the second
scheduler - the UL-BS scheduler - makes the allocation
decision based on the bandwidth requests from the MSs and
the associated QoS parameters. Several ways to send
bandwidth requests were described earlier in Section I.F.
Finally, the third scheduler is at the MS. Once the UL-BS
grants the bandwidth for the MS, the MS scheduler decides
which queues should use that allocation. Recall that while
the requests are per connections, the grants are per subscriber
and the subscriber is free to choose the appropriate queue to
service. The MS scheduler needs a mechanism to allocate the
bandwidth in an efficient way. Fig. 6 classification of
scheduler is given.
Figure 4. IEEE 802.16 reference model.
IV.
SCHEDULER
Scheduling is the main component of the MAC layer that
helps assure QoS to various service classes [12,13,14,16].
The scheduler works as a distributor to allocate the resources
among MSs. The allocated resource can be defined as the
number of slots and then these sots are mapped into a
number of subchannels (each subchannel is a group of
multiple physical subcarriers) and time duration (OFDM
symbols). In OFDMA, the smallest logical unit for
bandwidth allocation is a slot. The definition of slot depends
upon the direction of traffic (downlink/uplink) and
subchannelization modes. For example, in PUSC mode in
downlink, one slot is equal to twenty four subcarriers (one
subchannel) for three OFDM symbols duration. In the same
mode for uplink, one slot is fourteen subcarriers (one uplink
subchannel) for two OFDM symbols duration. The mapping
process from logical subchannel to multiple physical
subcarriers is called a permutation. PUSC, discussed above is
one of the permutation modes. Others include Fully Used
Subchannelization (FUSC) and Adaptive Modulation and
Coding (band-AMC). 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. After the
scheduler logically assigns the resource in terms of number
of slots, it may also have to consider the physical allocation,
e.g., the subcarrier allocation. In systems with Single Carrier
PHY, the scheduler assigns the entire frequency channel to a
MS. Therefore, the main task is to decide how to allocate the
number of slots in a frame for each user. In systems with
OFDM PHY, the scheduler considers the modulation
Figure 5. Component Schedulers at BS and MSs
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Most of data traffic falls into this category. This service
class guarantees neither delay nor throughput. The
bandwidth will be granted to the MS if and only if there is a
left-over bandwidth from other classes. In practice most
implementations allow specifying minimum reserved traffic
rate and maximum sustained traffic rate even for this class.
Schedulars
Channel Unaware
Intra Class
Key Objective
Channel Aware
Note that 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. Consider bandwidth request mechanisms for uplink.
UGS, ertPS and rtPS are real-time traffic. UGS has a static
allocation. ertPS is a combination of UGS and rtPS. Both
UGS and ertPS can reserve the bandwidth during setup.
Unlike UGS, ertPS allows all kinds of bandwidth request
including contention resolution. rtPS can not participate in
contention resolution. For other traffic classes (non real-time
traffic), nrtPS and BE, several types of bandwidth requests
are allowed such as piggybacking, bandwidth stealing,
unicast polling and contention resolution. These are further
discussed in Section I.F. Thus mobile WiMAX brings
potential benefits in terms of coverage, power consumption,
self-installation, frequency reuse, and bandwidth efficiency.
One of the key complications is that the incompatibility in
the newly introduced scalable OFDM (SOFDM) in IEEE
802.11e with the original OFDM scheme forces equipment
manufacturers to come up with mechanisms to ease the
transition
Fairness
QoS Guarantee
System
Inter Class
FIFO
RR,WRR,DRR
EDW,LWDF
Avg. Bw/Frame
wFQ
RR,WRR
Priority,DTPQ
Figure. 6. Classification of WiMAX schedulers
V.
WIMAX QOS SERVICE CLASSES
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. Table II presents a comparison of these classes
[15-16].
TABLE II.
UGS: This service class provides a fixed periodic
bandwidth allocation. Once the connection is setup, there is
no need to send any other requests. This service is designed
for constant bit rate (CBR) real-time traffic such as E1/T1
circuit emulation. The main QoS parameters are maximum
sustained rate (MST), maximum latency and tolerated jitter
(the maximum delay variation).
COMPARISON OF WIMAX QOSSERVICE CLASSES
QoS
Pros
Cons
Bandwidth may not be
utilized
fully
since
allocations are granted
regardless of current need
Need to use the polling
mechanism(to meet the
delay guarantee) and a
mechanism to let the BS
know when the traffic
starts during silent perios
Require the overhead of
bandwidth request and the
polling latency(to meet the
delay guarantee)
UGS
ertPS
Optimal
efficiency
nrtPS
Provide efficient service for
non-real-time
traffic
with
minimum reserved rate
N/A
BE
rtPS: This service class is for variable bit rate (VBR)
realtime traffic such as MPEG compressed video. Unlike
UGS, rtPS bandwidth requirements vary and so the BS needs
to regularly poll each MS to determine what allocations need
to be made. The QoS parameters are similar to the UGS but
minimum reserved traffic rate and maximum sustained traffic
rate need to be specified separately. For UGS and ertPS
services, these two parameters are the same, if present.
Optimal latency and
overhead efficiency
rtPS
ertPS: This service is designed to support VoIP with
silence suppression. No traffic is sent during silent periods.
ertPS service is similar to UGS in that the BS allocates the
maximum sustained rate in active mode, but no bandwidth is
allocated during the silent period. There is a need to have the
BS poll the MS during the silent period to determine if the
silent period has ended. The QoS parameters are the same as
those in UGS.
No overhead. Meet guaranteed
latency for real- time service
Provide efficient service for BE
traffic
No service guarantee,
some connections may
starve for long period of
time
data
VI.
data
transport
CONCLUSION
This paper presents an overview of the IEEE 802.16m
PHY layer issues ,MAC protocol, specifically issues
associated with scheduling and QoS provisioning. It also
discusses the main features of the newly standardized mobile
WiMAX, IEEE 802.16e to IEEE 802.16m. With the
introduction of mobile WiMAX technology, it can be
expected that future work will focus on the mobility aspect
and interoperability of mobile WiMAX with other wireless
nrtPS: This service class is for non-real-time VBR traffic
with no delay guarantee. Only minimum rate is guaranteed.
File Transfer Protocol (FTP) traffic is an example of
applications using this service class.
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technologies. For high quality voice and video, Internet and
mobility, demand for bandwidth is more. To address these
needs IEEE 802.16m appears as a strong candidate for
providing aggregate rates to high-speed mobile users at the
range of Gbps.
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