Wireless Local Area Network Networks Research Articles

Wireless video streaming over integrated 3G and WLAN networks

Media streaming is a popular application demanding high data rates and hard delay constraints. These requirements raise great challenges in the wireless environment, where signal fading, noise interference and network congestion introduce data losses or corruptions. Today, the availability of the Third Generation (3G) wireless system and the Wireless Local Area Network (WLAN) provides a broader bandwidth to cater for multimedia application. Different characteristics of 3G and WLAN networks result in different attributes in video streaming applications. In this paper, we propose a collaborative scheme across 3G and WLAN networks for video streaming, using layered video coding and Unequal Error Protection (UEP) to improve the perceived video quality.

Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff

This paper considers optimizing the utilization of radio resources in a heterogeneous integrated system consisting of two different networks: a wireless local area network (WLAN) and a wideband code division multiple access (CDMA) network. We propose a joint session admission control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over both the WLAN and the CDMA cellular networks. The WLAN operates under the IEEE 802.11e medium access control (MAC) protocol, which supports QoS for multimedia traffic. A novel concept of effective bandwidth is used in the CDMA network to derive the unified radio resource usage, taking into account both physical layer linear minimum mean square error (LMMSE) receivers and characteristics of the packet traffic. Numerical examples illustrate that the network revenue earned in the proposed joint admission control scheme is significantly larger than that when the individual networks are optimized independently with no vertical handoff between them. The revenue gain is also significant over the scheme in which vertical handoff is supported, but admission control is not done jointly. Furthermore, we show that the optimal joint admission control policy is a randomized policy, i.e., sessions are admitted to the system with probabilities in some states.

Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff

This paper considers optimizing the utilization of radio resources in a heterogeneous integrated system consisting of two different networks: a wireless local area network (WLAN) and a wideband code division multiple access (CDMA) network. We propose a joint session admission control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over both the WLAN and the CDMA cellular networks. The WLAN operates under the IEEE 802.11e medium access control (MAC) protocol, which supports QoS for multimedia traffic. A novel concept of effective bandwidth is used in the CDMA network to derive the unified radio resource usage, taking into account both physical layer linear minimum mean square error (LMMSE) receivers and characteristics of the packet traffic. Numerical examples illustrate that the network revenue earned in the proposed joint admission control scheme is significantly larger than that when the individual networks are optimized independently with no vertical handoff between them. The revenue gain is also significant over the scheme in which vertical handoff is supported, but admission control is not done jointly. Furthermore, we show that the optimal joint admission control policy is a randomized policy, i.e., sessions are admitted to the system with probabilities in some states

Optimal Joint Session Admission Control in Integrated WLAN and CDMA Cellular Networks with Vertical Handoff

This paper considers optimizing the utilization of radio resources in a heterogeneous integrated system consisting of two different networks: a wireless local area network (WLAN) and a wideband cod...

GPRS∕UMTS-aided authentication protocol for wireless LANs

Wireless local area network (WLAN) and cellular network are two important technologies for providing wireless communications. For user authentication of WLAN, the IEEE 802.1X standard provides an authentication framework that is based on the Extensible Authentication Protocol (EAP). When a roaming user wants to access WLANs provided by different operators, the user must remember multiple identities and the corresponding authentication credentials. Obviously, such an exercise is not user friendly. This problem is caused by the fact that a visited WLAN does not have the authentication credential of a roaming user. Previous proposals have studied the authentication of inter-network roaming across different WLANs, or across a cellular network and a WLAN. As is known, cellular networks provide wider service areas, ‘always-on’ and ubiquitous connectivity. The integration of WLAN and cellular networks has a management advantage that it can unify the subscriber identity and the corresponding credential. In this paper, we first propose a practical certificate distribution scheme. The certificate distribution scheme allows roaming users of a cellular network to obtain temporary certificates from their home cellular network. Afterward adopting certificate-based authentication protocol of the IEEE 802.1X standard, roaming users may use temporary certificates to access WLANs. The proposed solution achieves easy subscriber management and pervasive access. As demonstrated, the proposed solution also provides mutual authentication and strong identity protection, in addition to withstanding the man-in-the-middle attack and the eavesdropping attack. A performance evaluation shows that the proposed protocol is well suited for roaming users with mobile devices.

An approach for seamless handoff among mobile WLAN/GPRS integrated networks

Wireless local area networks (WLAN) and General Packet Ratio Service (GPRS) networks are two of the most widely used wireless network systems. In this paper, we propose a mobility support for mobile host roaming between WLAN and GPRS networks. In addition, a handoff decision model is presented to reduce the latency of the handoff procedure. The experimental results, including throughput, packet delay and handoff latency are given to show the performance of our approach.

Smart Handoff Scheme for Supporting Roaming between WLAN and GPRS Networks

Recent advancement in personal communication services (PCS) provides wireless multimedia services for users on the move. For establishing the convenient access environment, the evolution of IP-based integrated scheme becomes very urgent for public wireless access systems. In this paper, we clarify the well-known issues of integrating the general packet radio service (GPRS) network and IEEE 802.11 wireless local area network (WLAN). These issues include the inconsistence in transmission rate and coverage area, the difficulty in seamless handoff, the complexities of mobile IP and address translations, and so on. Based on classified cases, we propose the circular probe strategy (CPS) to solve the IP translations and measure the precise handoff latency of a mobile node roaming from one network to another. This latency information helps a mobile node and its home agent (HA) to decide the appropriate handoff timing, to maximize the data transmission rate, and to perform seamless handoff in the heterogeneous system. We also proposed the smart access point (AP) mechanism to reduce the overhead of CPS and to provide precise handoff latency information for mobile nodes (MNs) to select the most appropriate AP for association. Experiment results demonstrate that the proposed smart handoff scheme performs better than traditional algorithms in terms of handoff time in the integrated network.

Authentication and Billing Protocols for the Integration of WLAN and 3G Networks

Wireless communications have developed rapidly and have been applied for many services. Cellular (the third-generation) mobile networks and wireless local area network (WLAN) are two important technologies for providing wireless communications. The third-generation (3G) networks provide wider service areas, and “always-o” and ubiquitous connectivity with low-speed data rate. WLAN networks offer higher data rate and the easy compatibility of wired Internet, but cover smaller areas. In fact, 3G and WLAN possess complementary properties. Integrating 3G and WLAN networks may offer subscribers high-speed wireless data services and ubiquitous connectivity. For integrating two heterogeneous networks, several issues should be involved, authentication, billing, quality of service, and seamless roaming between 3G and WLAN networks. In this paper, we address the authentication and billing problems and propose two protocols that provide both authentication and billing services. One protocol utilizes a one-time password approach to authenticate subscribers. This protocol is efficient in both computation time and authentication procedures. Because of the restrictions of the password-based approach, this protocol could not offer the non-repudiation property for the billing problem. Another protocol is constructed on a public-key-based system (i.e., certificates). Although it requires more computation time than the password-based approach, non-repudiation is guaranteed. Performance analysis simulation results are given to validate our two protocols.

Wireless communication network design in IC factory

A wireless local area network (WLAN) is designed for an IC factory in Hong Kong using the hierarchical genetic algorithm (HGA). The HGA is capable of handling multiobjective functions and discrete constraints. Because of this uniqueness, together with the adoption of a Pareto ranking scheme, a solution can be reached even when skewed multiobjective functions and constraints confinements are being imposed. It has been found from this study that a precise number of base stations can be identified for the WLAN network, while it can satisfy a number of objectives and constraints. This added feature provides a further design tradeoff between cost and performance at no extra effort.