With rapid development of wireless technology, more and more applications can be served by wirele... more With rapid development of wireless technology, more and more applications can be served by wireless networks. To provide integrated service over wireless networks has become a very important issue in the design of wireless networks. In this paper, we propose a new MAC protocol with scheduling algorithms to provide integrated service for CDMA based wireless networks. This protocol evolves from the distributed queuing random access protocol for CDMA wireless network (DQRAP/CDMA). The proposed protocol has been designed to have an ability to accommodate integrated traffic in the network with effective scheduling schemes introduced. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol and scheduling algorithms. The results reveal that the proposed protocol with the scheduling performs effectively to the integrated traffic composed of message with or without time constraints and achieves fairness among different types of traffic
Numbers in the index correspond to the last two digits of the six-digit citation identifier (CID)... more Numbers in the index correspond to the last two digits of the six-digit citation identifier (CID) article numbering system used in Proceedings of SPIE. The first four digits reflect the volume number. Base 36 numbering is employed for the last two digits and indicates the order of articles within the volume. Numbers start with 00
International Journal of Communication Systems, Mar 2, 2017
In recent years, the vehicular ad hoc network has attracted worldwide attention from academe and ... more In recent years, the vehicular ad hoc network has attracted worldwide attention from academe and industry. Many researches have been executed to improve the quality of services (QoS) of the intelligent transportation system. However, current existing channel access schemes at the medium access control layer specified in 802.11 protocol, including hybrid coordination function control channel access (HCCA) and enhanced distributed channel access, could not efficiently achieve the QoS requirements in some special situations. This paper proposes a delay guaranteed HCCA (DG-HCCA) scheduling scheme, which works based on a Markov decision process model and the measurement of historic performance, to guarantee the QoS enhanced data transmission for vehicles to roadside unit. Besides, this paper also presents a performance analysis model to systematically evaluate the system performance of the channel utility and the average delay. The performance of the proposed delay guaranteed HCCA scheduling scheme is compared with that of original HCCA scheme specified in 802.11p standard and other 2 HCCA improved schemes by the simulation experiments. The simulation results demonstrate that the proposed solution could highly fulfill the transmission delay requirements with a better channel utility and less loss rates than those by the standard HCCA scheme and other 2 schemes.
Machine Type Communication (MTC), as one of the most important wireless communication technologie... more Machine Type Communication (MTC), as one of the most important wireless communication technologies in the future wireless communication, has become the new business growth point of mobile communication network. It is a key point to achieve seamless handovers within Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) for massive MTC (mMTC) devices in order to support mobility in the Long Term Evolution-Advanced (LTE-A) networks. When mMTC devices simultaneously roam from a base station to a new base station, the current handover mechanisms suggested by the Third-Generation Partnership Project (3GPP) require several handover signaling interactions, which could cause the signaling load over the access network and the core network. Besides, several distinct handover procedures are proposed for different mobility scenarios, which will increase the system complexity. In this paper, we propose a simple and secure uniform group-based handover authentication scheme for mMTC devices based on the multisignature and aggregate message authentication code (AMAC) techniques, which is to fit in with all of the mobility scenarios in the LTE-A networks. Compared with the current 3GPP standards, our scheme can achieve a simple authentication process with robust security protection including privacy preservation and thus avoid signaling congestion. The correctness of the proposed group handover authentication protocol is formally proved in the Canetti-Krawczyk (CK) model and verified based on the AVISPA and SPAN.
The Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN) h... more The Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN) has introduced IP technologies to wireless sensor networks, which significantly promotes the development of the Internet of Things (IoT). To support effective mobility management of these resource constrained IP-based sensor nodes, the Proxy Mobile IPv6 (PMIPv6) has been proposed as a standard to minimize the communication overhead of those nodes. Although the standard has specified some issues of security and mobility in 6LoWPANs, the issues of supporting secure group handovers have not been addressed much by the currently existing solutions. To further reduce the handover latency and signaling overhead, a fast group authentication scheme is proposed in this paper to support secure and seamless handovers for multiple resource constrained 6LoWPAN devices. With the consideration of mobile sensors with limited energy, only simple hash functions and symmetric encryption algorithms are used. The security analysis and the performance evaluation show that the proposed 6LoWPAN group handover scheme could enhance the security functionalities with high efficiency to achieve a fast authentication for handovers.
In the design of wireless communication networks, we may have to interconnect n stations locating... more In the design of wireless communication networks, we may have to interconnect n stations locating at given points in the plane such that the distance among each stations is as small as possible by introducing at most k extra stations subjective to a budget limit. In this paper, our goal is to determine the locations of the extra k stations interconnecting the existing n stations to minimize the longest distance among stations. This is so-called bottleneck Steiner tree problem, which also has applications in VLSI routing, WDM optical networks design and phylogenetic tree reconstruction. The problem has been proved to be NP-hard and cannot be approximated in the performance ratio 2 in polynomial time in both Euclidean and rectilinear plane and approximation algorithms in the best possible performance ratios presented for the problem in both planes. In this paper, we improve the time complexity of the approximation algorithms and conduct simulations to demonstrate the validness of our improvements.
The requirement on providing real-time data service by wireless networks is a critical issue in t... more The requirement on providing real-time data service by wireless networks is a critical issue in the design of current wireless networks. Distributed queueing request update multiple access (DQRUMA) is proposed as a demand assignment medium access control (MAC) protocol to efficiently control the medium sharing by multiple mobile users. With help of a packet transmission policy, DQRUMA has a potential to provide QoS service for the time-constrained burst data traffic. In this paper, we study the problem of providing real-time service to the ATM packets with or without time constraints in the wireless networks. In particular, we propose a novel scheduling scheme for the DQRUMA protocol to control the packet transmission in the wireless packet-switched networks. We have conducted extensive simulation experiments to evaluate the performance of the proposed algorithm and compare its real-time performance with those of other packet transmission policies. This study proves that the new algorithm is an efficient transmission policy for the DQRUMA to support real-time service in wireless networks.
Machine Type Communication (MTC) as one of the most important wireless communication technologies... more Machine Type Communication (MTC) as one of the most important wireless communication technologies in the future wireless communication, has become the new business growth point of mobile communication network. It is a key point to achieve seamless handovers within Evolved Universal Terrestrial Radio Access Network (E-UTRAN) for a large number of MTC devices in order to support mobility in the Long Term Evolution Advanced (LTE-A) networks. When a good deal of MTC devices simultaneously roam from a base station to another, the current handover mechanisms suggested by the third Generation Partnership Project (3GPP) require several handover signaling interactions, which could cause the signaling load over the network nodes. Besides, several distinct handover procedures are proposed for different mobility scenarios, which will increase the system complexity. In this paper, we propose a simple and secure uniform group-based handover authentication scheme for a lot of MTC devices based on the multi-signature and aggregate message authentication codes (AMAC) techniques, which is to fit in with all of the mobility scenarios in the LTE-A networks. Compared with the current 3GPP standards, our scheme can achieve a simple authentication process with robust security protection, and thus avoid signaling congestion.
With the continuous development of mobile communication technologies, Third Generation Partnershi... more With the continuous development of mobile communication technologies, Third Generation Partnership Project (3GPP) has proposed related standards with the fifth generation mobile communication technology (5G), which marks the official start of the evolution from the current Long Term Evolution (LTE) system to the next generation mobile communication system (5GS). This paper makes a large number of contributions to the security aspects of 3GPP 5G networks. Firstly, we present an overview of the network architecture and security functionality of the 3GPP 5G networks. Subsequently, we focus on the new features and techniques including the support of massive Internet of Things (IoT) devices, Device to Device (D2D) communication, Vehicle to Everything (V2X) communication, and network slice, which incur the huge challenges for the security aspects in 3GPP 5G networks. Finally, we discuss in detail the security features, security requirements or security vulnerabilities, existing security solutions and some open research issues about the new features and techniques in 3GPP 5G network.
If LTE has made it possible to stream music and video over mobile devices such as smartphones and... more If LTE has made it possible to stream music and video over mobile devices such as smartphones and tablets, 5G will enable vehicles, sensors, and other countless devices to interact and share data over the cellular network. To unleash the full potential of 5G, it is imperative to address the shortcomings of LTE in regard to mobility management. One major challenge with LTE is improving the handover performance and security. In order to enhance the performance and security of the handover process, this paper introduces an approach using blockchain for key derivation and key sharing. This novel approach, Blockchain Key Derivation Function (BKDF), ensures tighter security as well as faster handover between the base stations. With blockchain adding an extra layer of security, the network is able to securely derive the handover key and share it with the base stations and mobile devices in the pre-handover phase, which significantly reduces the number of operations required during the intra-handover phase. A formal security analysis on BKDF is conducted with the Burrows-Abadi-Needham (BAN) logic, followed by an analysis on the effectiveness of BKDF against some of the well-known types of network attacks. The simulation results confirm that BKDF reduces handover latency and improves link stability with decrease in packet loss in the intra-handover phase.
WiMax is the wireless metropolitan area network for broadband wireless communications. In IEEE 80... more WiMax is the wireless metropolitan area network for broadband wireless communications. In IEEE 802.16e, the mobility support has been defined to handle the handovers for the continuity of the active services when the mobile stations move across the air interfaces of sectors. The overall handover process includes the scanning process to select the suitable neighbor base station as the target
QoS provisioning is an important issue in the deployment of broadband wireless access networks wi... more QoS provisioning is an important issue in the deployment of broadband wireless access networks with real-time and non-real-time traffic integration. An opportunistic MAC (OMAC) combines cross-layer design features with opportunistic scheduling scheme to achieve high system utilization while providing QoS support to various applications. A single scheduling algorithm cannot guarantee all the QoS requirements of traffics without the support of a suitable CAC and vice versa. In this paper, we propose a cross-layer MAC scheduling framework and a corresponding opportunistic scheduling algorithm in tandem with the CAC algorithm to support QoS in WiMAX point-to-multipoint (PMP) networks. Extensive experimental simulations have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can improve the performance of WiMAX networks in terms of packet delay, packet loss rate and throughput. The proposed CAC scheme can guarantee the admitted connections to meet their QoS requirements.
In recent years, the wireless LAN has evolved as an increasingly popular solution for providing w... more In recent years, the wireless LAN has evolved as an increasingly popular solution for providing wireless access to the Internet. The first part of the tutorial will discuss the basics of wireless LAN technology focusing on the physical layer, medium access control layer, and protocol stack of the wireless LAN. The integration of the wireless LAN with 3G cellular networks will be discussed next as a further development of the wireless LAN. Currently, several 3G standards have been developed and their air interfaces are based on either CDMA or TDMA technology. CDMA technology is one of the most widely adopted 3G air interfaces. WCDMA is one of the 3G standards and is standardized within 3GPP. WCDMA has two modes, FDD and TDD. The WCDMA systems and products based on Rel'99 have just started to appear to the market.
With the proliferation of the worldwide web (WWW), current local and wide area networks can hardl... more With the proliferation of the worldwide web (WWW), current local and wide area networks can hardly cope with the huge demand for network bandwidth. As a result, there is a worldwide effort in upgrading current networks with highcapacity fiber-optic links that can potentially deliver Tera-bits/sec bandwidth. The Wavelength-Division-Multiplexing (WDM) is an effective technique for utilizing the large bandwidth of an optical fiber. By allowing multiple simultaneous transmission over a number of channels, WDM has the potential to significantly improve the performance of optical networks. The nodes in the network can transmit and receive messages on any of the available channels by employing one or more tunable transmitter(s) and/or tunable receiver(s). Several topologies have been proposed for WDM networks. Of particular interest to us in this
Medium Access Control (MAC) protocol design plays a very important role in the design of wireless... more Medium Access Control (MAC) protocol design plays a very important role in the design of wireless networks. In this paper, we propose a new MAC protocol to provide real-time service for a CDMA wireless network. This protocol has been designed based on the distributed queuing random access protocol for CDMA wireless networks (DQRAP/CDMA). As real-time scheduling schemes have been introduced into the protocol design, the new protocol has an ability to accommodate real-time traffic in the CDMA wireless networks. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol. The results reveal that the proposed protocol can efficiently provide real-time service to the traffic composed of time constrained messages in the CDMA wireless networks.
This chapter presents QoS support mechanisms in WiMax networks. Existing proposals with the state... more This chapter presents QoS support mechanisms in WiMax networks. Existing proposals with the state-of-the-art technology have been classified into three main categories: QoS support architecture, Bandwidth management mechanism and Traffic management mechanism. Representative schemes from each of the categories have been evaluated with respect to major distinguishing characteristics of the WiMax MAC layer and PHY layer as specified in the IEEE 802.16d standard. Future research issues and trends are also highlighted.
With rapid development of wireless technology, more and more applications can be served by wirele... more With rapid development of wireless technology, more and more applications can be served by wireless networks. To provide integrated service over wireless networks has become a very important issue in the design of wireless networks. In this paper, we propose a new MAC protocol with scheduling algorithms to provide integrated service for CDMA based wireless networks. This protocol evolves from the distributed queuing random access protocol for CDMA wireless network (DQRAP/CDMA). The proposed protocol has been designed to have an ability to accommodate integrated traffic in the network with effective scheduling schemes introduced. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol and scheduling algorithms. The results reveal that the proposed protocol with the scheduling performs effectively to the integrated traffic composed of message with or without time constraints and achieves fairness among different types of traffic
Numbers in the index correspond to the last two digits of the six-digit citation identifier (CID)... more Numbers in the index correspond to the last two digits of the six-digit citation identifier (CID) article numbering system used in Proceedings of SPIE. The first four digits reflect the volume number. Base 36 numbering is employed for the last two digits and indicates the order of articles within the volume. Numbers start with 00
International Journal of Communication Systems, Mar 2, 2017
In recent years, the vehicular ad hoc network has attracted worldwide attention from academe and ... more In recent years, the vehicular ad hoc network has attracted worldwide attention from academe and industry. Many researches have been executed to improve the quality of services (QoS) of the intelligent transportation system. However, current existing channel access schemes at the medium access control layer specified in 802.11 protocol, including hybrid coordination function control channel access (HCCA) and enhanced distributed channel access, could not efficiently achieve the QoS requirements in some special situations. This paper proposes a delay guaranteed HCCA (DG-HCCA) scheduling scheme, which works based on a Markov decision process model and the measurement of historic performance, to guarantee the QoS enhanced data transmission for vehicles to roadside unit. Besides, this paper also presents a performance analysis model to systematically evaluate the system performance of the channel utility and the average delay. The performance of the proposed delay guaranteed HCCA scheduling scheme is compared with that of original HCCA scheme specified in 802.11p standard and other 2 HCCA improved schemes by the simulation experiments. The simulation results demonstrate that the proposed solution could highly fulfill the transmission delay requirements with a better channel utility and less loss rates than those by the standard HCCA scheme and other 2 schemes.
Machine Type Communication (MTC), as one of the most important wireless communication technologie... more Machine Type Communication (MTC), as one of the most important wireless communication technologies in the future wireless communication, has become the new business growth point of mobile communication network. It is a key point to achieve seamless handovers within Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) for massive MTC (mMTC) devices in order to support mobility in the Long Term Evolution-Advanced (LTE-A) networks. When mMTC devices simultaneously roam from a base station to a new base station, the current handover mechanisms suggested by the Third-Generation Partnership Project (3GPP) require several handover signaling interactions, which could cause the signaling load over the access network and the core network. Besides, several distinct handover procedures are proposed for different mobility scenarios, which will increase the system complexity. In this paper, we propose a simple and secure uniform group-based handover authentication scheme for mMTC devices based on the multisignature and aggregate message authentication code (AMAC) techniques, which is to fit in with all of the mobility scenarios in the LTE-A networks. Compared with the current 3GPP standards, our scheme can achieve a simple authentication process with robust security protection including privacy preservation and thus avoid signaling congestion. The correctness of the proposed group handover authentication protocol is formally proved in the Canetti-Krawczyk (CK) model and verified based on the AVISPA and SPAN.
The Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN) h... more The Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN) has introduced IP technologies to wireless sensor networks, which significantly promotes the development of the Internet of Things (IoT). To support effective mobility management of these resource constrained IP-based sensor nodes, the Proxy Mobile IPv6 (PMIPv6) has been proposed as a standard to minimize the communication overhead of those nodes. Although the standard has specified some issues of security and mobility in 6LoWPANs, the issues of supporting secure group handovers have not been addressed much by the currently existing solutions. To further reduce the handover latency and signaling overhead, a fast group authentication scheme is proposed in this paper to support secure and seamless handovers for multiple resource constrained 6LoWPAN devices. With the consideration of mobile sensors with limited energy, only simple hash functions and symmetric encryption algorithms are used. The security analysis and the performance evaluation show that the proposed 6LoWPAN group handover scheme could enhance the security functionalities with high efficiency to achieve a fast authentication for handovers.
In the design of wireless communication networks, we may have to interconnect n stations locating... more In the design of wireless communication networks, we may have to interconnect n stations locating at given points in the plane such that the distance among each stations is as small as possible by introducing at most k extra stations subjective to a budget limit. In this paper, our goal is to determine the locations of the extra k stations interconnecting the existing n stations to minimize the longest distance among stations. This is so-called bottleneck Steiner tree problem, which also has applications in VLSI routing, WDM optical networks design and phylogenetic tree reconstruction. The problem has been proved to be NP-hard and cannot be approximated in the performance ratio 2 in polynomial time in both Euclidean and rectilinear plane and approximation algorithms in the best possible performance ratios presented for the problem in both planes. In this paper, we improve the time complexity of the approximation algorithms and conduct simulations to demonstrate the validness of our improvements.
The requirement on providing real-time data service by wireless networks is a critical issue in t... more The requirement on providing real-time data service by wireless networks is a critical issue in the design of current wireless networks. Distributed queueing request update multiple access (DQRUMA) is proposed as a demand assignment medium access control (MAC) protocol to efficiently control the medium sharing by multiple mobile users. With help of a packet transmission policy, DQRUMA has a potential to provide QoS service for the time-constrained burst data traffic. In this paper, we study the problem of providing real-time service to the ATM packets with or without time constraints in the wireless networks. In particular, we propose a novel scheduling scheme for the DQRUMA protocol to control the packet transmission in the wireless packet-switched networks. We have conducted extensive simulation experiments to evaluate the performance of the proposed algorithm and compare its real-time performance with those of other packet transmission policies. This study proves that the new algorithm is an efficient transmission policy for the DQRUMA to support real-time service in wireless networks.
Machine Type Communication (MTC) as one of the most important wireless communication technologies... more Machine Type Communication (MTC) as one of the most important wireless communication technologies in the future wireless communication, has become the new business growth point of mobile communication network. It is a key point to achieve seamless handovers within Evolved Universal Terrestrial Radio Access Network (E-UTRAN) for a large number of MTC devices in order to support mobility in the Long Term Evolution Advanced (LTE-A) networks. When a good deal of MTC devices simultaneously roam from a base station to another, the current handover mechanisms suggested by the third Generation Partnership Project (3GPP) require several handover signaling interactions, which could cause the signaling load over the network nodes. Besides, several distinct handover procedures are proposed for different mobility scenarios, which will increase the system complexity. In this paper, we propose a simple and secure uniform group-based handover authentication scheme for a lot of MTC devices based on the multi-signature and aggregate message authentication codes (AMAC) techniques, which is to fit in with all of the mobility scenarios in the LTE-A networks. Compared with the current 3GPP standards, our scheme can achieve a simple authentication process with robust security protection, and thus avoid signaling congestion.
With the continuous development of mobile communication technologies, Third Generation Partnershi... more With the continuous development of mobile communication technologies, Third Generation Partnership Project (3GPP) has proposed related standards with the fifth generation mobile communication technology (5G), which marks the official start of the evolution from the current Long Term Evolution (LTE) system to the next generation mobile communication system (5GS). This paper makes a large number of contributions to the security aspects of 3GPP 5G networks. Firstly, we present an overview of the network architecture and security functionality of the 3GPP 5G networks. Subsequently, we focus on the new features and techniques including the support of massive Internet of Things (IoT) devices, Device to Device (D2D) communication, Vehicle to Everything (V2X) communication, and network slice, which incur the huge challenges for the security aspects in 3GPP 5G networks. Finally, we discuss in detail the security features, security requirements or security vulnerabilities, existing security solutions and some open research issues about the new features and techniques in 3GPP 5G network.
If LTE has made it possible to stream music and video over mobile devices such as smartphones and... more If LTE has made it possible to stream music and video over mobile devices such as smartphones and tablets, 5G will enable vehicles, sensors, and other countless devices to interact and share data over the cellular network. To unleash the full potential of 5G, it is imperative to address the shortcomings of LTE in regard to mobility management. One major challenge with LTE is improving the handover performance and security. In order to enhance the performance and security of the handover process, this paper introduces an approach using blockchain for key derivation and key sharing. This novel approach, Blockchain Key Derivation Function (BKDF), ensures tighter security as well as faster handover between the base stations. With blockchain adding an extra layer of security, the network is able to securely derive the handover key and share it with the base stations and mobile devices in the pre-handover phase, which significantly reduces the number of operations required during the intra-handover phase. A formal security analysis on BKDF is conducted with the Burrows-Abadi-Needham (BAN) logic, followed by an analysis on the effectiveness of BKDF against some of the well-known types of network attacks. The simulation results confirm that BKDF reduces handover latency and improves link stability with decrease in packet loss in the intra-handover phase.
WiMax is the wireless metropolitan area network for broadband wireless communications. In IEEE 80... more WiMax is the wireless metropolitan area network for broadband wireless communications. In IEEE 802.16e, the mobility support has been defined to handle the handovers for the continuity of the active services when the mobile stations move across the air interfaces of sectors. The overall handover process includes the scanning process to select the suitable neighbor base station as the target
QoS provisioning is an important issue in the deployment of broadband wireless access networks wi... more QoS provisioning is an important issue in the deployment of broadband wireless access networks with real-time and non-real-time traffic integration. An opportunistic MAC (OMAC) combines cross-layer design features with opportunistic scheduling scheme to achieve high system utilization while providing QoS support to various applications. A single scheduling algorithm cannot guarantee all the QoS requirements of traffics without the support of a suitable CAC and vice versa. In this paper, we propose a cross-layer MAC scheduling framework and a corresponding opportunistic scheduling algorithm in tandem with the CAC algorithm to support QoS in WiMAX point-to-multipoint (PMP) networks. Extensive experimental simulations have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can improve the performance of WiMAX networks in terms of packet delay, packet loss rate and throughput. The proposed CAC scheme can guarantee the admitted connections to meet their QoS requirements.
In recent years, the wireless LAN has evolved as an increasingly popular solution for providing w... more In recent years, the wireless LAN has evolved as an increasingly popular solution for providing wireless access to the Internet. The first part of the tutorial will discuss the basics of wireless LAN technology focusing on the physical layer, medium access control layer, and protocol stack of the wireless LAN. The integration of the wireless LAN with 3G cellular networks will be discussed next as a further development of the wireless LAN. Currently, several 3G standards have been developed and their air interfaces are based on either CDMA or TDMA technology. CDMA technology is one of the most widely adopted 3G air interfaces. WCDMA is one of the 3G standards and is standardized within 3GPP. WCDMA has two modes, FDD and TDD. The WCDMA systems and products based on Rel'99 have just started to appear to the market.
With the proliferation of the worldwide web (WWW), current local and wide area networks can hardl... more With the proliferation of the worldwide web (WWW), current local and wide area networks can hardly cope with the huge demand for network bandwidth. As a result, there is a worldwide effort in upgrading current networks with highcapacity fiber-optic links that can potentially deliver Tera-bits/sec bandwidth. The Wavelength-Division-Multiplexing (WDM) is an effective technique for utilizing the large bandwidth of an optical fiber. By allowing multiple simultaneous transmission over a number of channels, WDM has the potential to significantly improve the performance of optical networks. The nodes in the network can transmit and receive messages on any of the available channels by employing one or more tunable transmitter(s) and/or tunable receiver(s). Several topologies have been proposed for WDM networks. Of particular interest to us in this
Medium Access Control (MAC) protocol design plays a very important role in the design of wireless... more Medium Access Control (MAC) protocol design plays a very important role in the design of wireless networks. In this paper, we propose a new MAC protocol to provide real-time service for a CDMA wireless network. This protocol has been designed based on the distributed queuing random access protocol for CDMA wireless networks (DQRAP/CDMA). As real-time scheduling schemes have been introduced into the protocol design, the new protocol has an ability to accommodate real-time traffic in the CDMA wireless networks. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol. The results reveal that the proposed protocol can efficiently provide real-time service to the traffic composed of time constrained messages in the CDMA wireless networks.
This chapter presents QoS support mechanisms in WiMax networks. Existing proposals with the state... more This chapter presents QoS support mechanisms in WiMax networks. Existing proposals with the state-of-the-art technology have been classified into three main categories: QoS support architecture, Bandwidth management mechanism and Traffic management mechanism. Representative schemes from each of the categories have been evaluated with respect to major distinguishing characteristics of the WiMax MAC layer and PHY layer as specified in the IEEE 802.16d standard. Future research issues and trends are also highlighted.
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