WLAN Environment Research Articles

FAMH: Fast Inter-Subnet Multicast Handoff Method for IEEE 802.11 WLANs

When a mobile node that subscribes to one or more multicast groups moves to another subnet, it is essential to provide a network level multicast handoff mechanism. Previous multicast handoff schemes are based on Mobile IP. However it is known that the Mobile IP is not adequate to interactive multimedia applications such as voice over IP or video conferencing due to its large handoff delay. Additionally, few researches have paid attentions on multicast handoff in infrastructure-mode WLAN environment. This paper proposes a fast inter-subnet multicast handoff method in Mobile IP based infrastructure-mode IEEE 802.11 WLAN environment. We introduce a dedicated Multicast Access Point (MAP) that works with an access points specified in standard IEEE 802.11 WLAN in order to alleviate disruption of receiving multicast datagram. Unlike previous research, our scheme does not modify Mobile IP specifications. MAP detects the completion of link-layer handoff, sends unsolicited IGMP Membership report to its local router on behalf of the mobile station and performs unicast tunneling. We evaluate the proposed method using ns-2 simulation. The simulation result shows that the proposed method can reduce the disruption period due to inter-subnet multicast handoff to about 1/12 and the packet loss rate can be reduced to about 1/4 over 20-size multicast group compared with the standard Mobile IP based IEEE 802.11 WLAN.

Fast handover support in a WLAN environment: challenges and perspectives

While handover management has traditionally used radio-technology-specific mechanisms, the need for integration of this diverse network environment has obviated the push of the handover functionality to the generic IP layer that serves the rendezvous point of underlying technologies. In this context, we study and analyze the implications of the link-layer agnostic operation of IP handover control on handover performance, having as a reference the fast mobile IPv6 protocol. We show that the behavior of the protocol (i.e., whether a reactive or proactive operation will be executed) is highly dependent on the timely availability of link layer information. A non-exhaustive list of generic link-layer triggers used for this purpose, as identified by the IEEE 802.21 WG, is also presented. Last, we apply this generic framework to a WLAN environment running fast mobile IPv6 and study the improvements in fast handoff support.

Services in interworking 3G and WLAN environments

Interworking WLANs and 3G mobile networks are expected to provide ubiquitous wireless communications at high data rates and a large variety of services with variable bandwidth and QoS requirements, across a wide range of propagation environments and mobility conditions, using dual mode terminals. The interworking of the two networks is a major step toward a new generation of wireless networks in which other radio technologies are also be integrated. In this article we present possible architectures that enable the interworking of 3G and WLAN networks. We then address the capabilities of various terminal types and describe future services in the interworking environment. Finally, we present market forecasts on terminal and service demand growth.

Integration of wireless LAN and 3G wireless - Policy-based QoS management architecture in an integrated UMTS and WLAN environment

Strong demands for public wireless broadband services will require more capacity than even that can be,supplied by advanced mobile cellular systems like the Universal Mobile Telecommunication System. The increasing popularity of WLANs has prompted mobile network operators to consider their deployment in high-density usage areas like indoor/outdoor public hotspots to provide complementary broadband access to their UMTS networks. In order to provide consistent QoS control over an integrated UMTS and WLAN system, a policy-based multidomain QoS management architecture is proposed in this article. Different UMTS-WLAN interworking scenarios are discussed to illustrate the feasibility of the proposed architecture.

JPEG2000 and MJPEG2000 transmission in 802.11 wireless local area networks

In this paper the transmission of JPEG2000 and motion JPEG2000 codestream in 802.11 WLAN environment is analyzed. The issues related to the transmission of JPEG2000, using non-reliable protocols as UDP-RTP, are investigated and a proper protection scheme for dealing with such an environment is presented, along with the obtained performance with different systems parameters. The proposed technique addresses a wide range of multimedia applications such as wireless PC to digital projector multimedia presentations, point to multipoint digital slide projection, wireless video-surveillance systems.

A distributed fair scheduling scheme in wireless LAN

This paper proposes an algorithm named WLFVC, which is a fully distributed wireless packet scheduling algorithm based on LFVC (Leap Forward Virtual Clock), to provide streams with fairness, especially in the short time scale. This algorithm is able to allocate bandwidth to streams proportional to their weights. Thus, better delay and jitter performance can be achieved. Since collisions and wireless link error degrade the performance of MAC protocols in the WLAN environment, WLFVC also takes them into consideration. Finally, this algorithm works in a fully distributed way and it can coexist with other stations that only support DCF (Distributed Coordination Function).

Public access mobility LAN: extending the wireless internet into the LAN enwronment

Public wireless communications will increasingly extend into wireless LAN environments in order to meet the ubiquitous access, high data rate, and local services demands of future Internet appliances. This article offers architectural guidelines for relatively large-scale IP-based WLAN environments configured to accept public access by mobile/portable appliances. By relying on IP-level service mechanisms at the access point, independent of the wireless medium access technology, the WLAN can simultaneously support different air interfaces, franchises for multiple service providers with effective authentication and billing, and a multisegment LAN environment including handoffs. QoS across the air interface is not addressed; this article rather concerns architecture of the wired LAN environment in which wireless access points are imbedded, and its capabilities for QoS and support of the business model.