http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12037 Masters Research - Master of Philosophy (MPhil) 2012-11-20T00:38:54.478Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:11305 Research Doctorate - Doctor of Philosophy (PhD) 2012-08-21T06:59:05.600Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:10702 Heterogeneity and convergence are two distinctive connotations of future wireless networks emanated from International Telecommunications Union (ITU)’s vision of Optimally Connected, Anywhere, Anytime. Multiple access networks, multiple terminals and multiple services are expected to converge in a manner where heterogeneity can be exploited to realize this ultimate goal. This raises the importance of radio resource management (RRM) for a multiple radio access technologies (multi-RAT) environment, where coalitions of heterogeneous access networks are each connected to a common Internet Protocol (IP)-based core network. In this article, we develop a cooperative RRM framework for future IP-based multi-RAT environment to coordinate better utilization of radio resources in an opportunistic yet altruistic manner. We motivate the importance of cooperation which can exploit heterogeneity as an enabler to improve system capacity and quality of service (QoS) of users. We exemplify the proof of concept based on a heterogeneous multiple access points (multi-AP) wireless local area network (WLAN) and argue that our technology agnostic approach is readily applicable to future IP-based multi-RAT environment. We demonstrate that our cooperative RRM framework benefits from the unified actions of joint optimization and results in a QoS-balanced system by enabling different functional entities to form synergies and multiple access networks to interact. We further show that a QoS-balanced system has salient traits of providing statistical QoS guarantee to support demanding multimedia applications while maximizing overall system capacity. Consequently, we advocate the notion of QoS balancing as criterion to quantify the state of balance in future IP-based multi-RAT environment. 2012-04-24T06:43:17.341Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5976 Always best connected (ABC) services allows multi- mode mobile terminals to stay connected to the best available networks, at anytime according to user preferences. One of the key aspects in realizing such ABC service is mainly attributed to an effective and dynamic access network selection process. However, most of the previous works consider the access network selection process as a static optimization problem which fails to address the dynamic QoS conditions intrinsic in wireless networks. One of the main challenges remains as no efficient way in obtaining dynamic QoS parameters such as packet delay, packet loss and jitter. In this paper, we proposed a novel dynamic access network selection algorithm capable of adapting to prevailing network conditions. Our algorithm is a dual stage estimation process where network selection performed using sequential Bayesian estimation relies on dynamic QoS parameters estimated through bootstrap approximation. Simulations demonstrate the effectiveness of our proposed algorithm which outperforms static optimization approach in a highly efficient manner. 2012-03-12T06:46:30.605Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6211 With the emerging IEEE 802.11n standard, the WLAN is poised as a promising ubiquitous networking technology to support multimedia applications where providing QoS becomes imperative. However, the 802.11 WLAN is not designed to support delay sensitive traffic. This problem is magnified during a handover and typically results in excessive handover latency and packet loss. In addition, a 802.11 WLAN handover process is predominantly based on the physical layer detection without QoS considerations. This often causes overloading of access points and consequently all its associated connections would suffer from high delay. The former can be resolved by reducing handover latency to achieve seamless handover and the latter can be mitigated by employing link layer detection in the 802.11 WLAN handover process and having an appropriate admission control scheme. Although the IEEE 802.11e standard supports prioritized QoS, it cannot guarantee strict QoS required by real-time services under heavy load. In this paper, we proposed an integrated load balancing scheme incorporating (i) QoS-based fast handover to support seamless handover by eliminating both detection and scanning phases from the 802.11 WLAN handover process; and (ii) soft admission control to protect QoS of existing connections when resources are low. This synergy allows us to perform QoS-related handover opportunistically and guarantees service QoS during and after handover respectively. Simulations showed that our proposed integrated load balancing scheme is capable of providing seamless handover and QoS provisioning for real-time VoIP services in terms of bounded delay and packet loss when considering multimedia traffic. Particularly, our proposed scheme exhibits both throughput and QoS fairness which jointly optimize overall system utilization. 2012-03-12T06:45:08.232Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6152 With proliferation of the IEEE 802.11 WLAN and the emerging 802.11n standard, the WLAN is poised as a promising ubiquitous networking technology to support VoIP services, which is gaining popularity due to their high cost efficiency. However, the 802.11 WLAN is not designed to support delay sensitive traffic such as VoIP. This problem is magnified during a handover as user roam the WLAN network resulting in excessive handover latency and consequently packet loss. In addition, a 802.11 WLAN handover process is predominantly based on the physical layer detection without QoS considerations. This often causes overloading of access points and consequently all its associated connections would suffer from high delay, resulting in unacceptable QoS for the VoIP services. The former can be resolved by reducing handover latency to achieve seamless handover and the latter can be mitigated by employing link layer detection in the 802.11 WLAN handover process and having an appropriate admission control scheme. In this paper, we proposed an integrated load balancing scheme incorporating (i) QoS-based fast handover to support seamless handover by eliminating both detection and scanning phases from the 802.11 WLAN handover process; and (ii) soft admission control to protect QoS of existing voice connections when resources are low. This synergy guarantees service QoS during and after handover respectively. Simulations showed that our proposed integrated load balancing scheme is capable of providing seamless handover and QoS enhancements in terms of increased throughput, reduced packet loss and bounded delay when considering heterogeneous voice traffic of different packetization intervals. Particularly, our proposed scheme effectuate QoS balance of both delay and throughput which jointly optimize overall system utilization. 2012-03-07T23:20:04.632Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6803 Research Doctorate - Doctor of Philosophy (PhD) 2011-12-07T21:40:11.206Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3026 As the demand for broadband multimedia wireless services increases, the need to provide QoS and higher data rate enhancements to the widely deployed IEEE 802.11 wireless LAN standard has become apparent. We propose a class-based adaptive ARQ scheme with QoS support for multimedia traffic, to facilitate higher throughputs through the reduction of MAC overhead. This scheme operates on top of the EDCA (enhanced distributed channel access) mechanism proposed in the IEEE 802.11e draft standard, which provides QoS support in the MAC layer through the use of service differentiation and traffic class prioritization. An OPNET simulation model is used to show that the proposed ARQ enhancement increases system performance. 2010-09-15T04:52:03.277Z ]]>