Spectrum handoff management in cognitive hetnet systems overlaid with femtocells

Cognitive radio networks can facilitate seamless mobility to users considering their effective use of the dynamic spectrum access. This is performed by proactive/reactive adaptation of transmission operations in response to the wireless environment changes. One of these operations includes handoff between various wireless domains. The handoff here is not just a registration with a new base station, but it is also a negotiation to get access to the available channels locally in coexistence with the primary users. This dynamic adaptation between channels, known as spectrum handoff (SH), significantly impacts the time of handoff reconnection, which raises many questions about the functioning of the cognitive radio solution in the next generation of network systems. Therefore, it is necessary to develop a new method for roaming mobile users, particularly networks that employ small cells such as femtocells in order to reduce the unnecessary channel adaptations. This paper proposes a new entity, namely, channel assigning agent for managing SH, operator database, and channel access authentication. The goal of this mechanism is to retain the same channel used by a mobile user whenever possible to improve network performance by reducing the unnecessary SHs. The modeling and efficiency of the proposed scheme are validated through simulation results. The proposed solution improves the accessibility of resources and stability ofmobile radio connections that benefits mobile users as well as operators

Mobility and QoS support in 4G wireless networks

Fourth-generation (4G) wireless networks will be the IP-based cellular networks integrating Internet with the existing cellular networks. Two important issues should be concerned in the IP-based cellular networks, IP mobility, and quality-of-service (QoS) guarantees. In this paper, we proposed two mechanisms to solve the problems with IP mobility and RSVP-based QoS provisioning. First, virtual-IP (VIP) allocation scheme in areas with a large rate of handoff can minimize the wireless signaling overhead due to IP mobility. The access routers (ARs) create dynamically the VIP zone by using the measured handoff rate derived from the history of the handolf into neighboring ARs. We show that VIP allocation scheme reduces the binding update messages in the wireless link than hierarchical mobile IPv6. Second, the new advance resource reservation protocol called proportional aggregate RSVP (PA-RSVP) can minimize waste of bandwidth and soft state refresh overhead due to IP mobility. It allocates the bandwidth in advance between the mobility anchor point and neighboring ARs using proportional aggregate reservation. We also show that PA-RSVP provides an improved performance over existing protocols