Roaming In Wireless Networks Research Articles

Navigation-driven handoff minimization in wireless networks

Interactive wireless Internet applications (e.g. VoIP over wireless networks, realtime monitoring and some mobile-cloud offloading applications) desire high-quality links and smooth connectivity during movement. In order to support seamless roaming in wireless networks, handoff optimization constantly attracted a lot of attentions. Most existing approaches aim at reducing handoff latency by modifying the communication and association protocols. While these methods provide significant savings in handoff latency, frequent handoffs could still be crucial and problematic for interactive applications. In this paper, we propose a new method for handoff optimization by introducing navigation to minimize the handoff frequency. We first formulate the navigation-driven handoff minimization problem in general case, then propose an optimal algorithm to the scenario of global knowledge, a heuristic localized algorithm for scenario of local knowledge, and a measurement-based algorithm for scenario of real communication settings. Implementation issues of the proposed algorithms are discussed and simulations based on real world AP deployment are used to evaluate their performance. Experiment results show that our algorithms reduce handoff frequency by 23% in average, compared to existing strategies. Extensive experiments of the impact of the high-layer QoS performance are also conducted to prove the effectiveness of our work.

TEASE: A novel Tunnel-based sEcure Authentication SchemE to support smooth handoff in IEEE 802.11 wireless networks

With the growing popularity of WiFi-based devices, WiFi-based wireless networks have received a great deal of interest in the wireless networks community. However, due to the limited transmission range of WiFi-based networks, mobile users have to switch their associated access points constantly to maintain continuing communications during their movement. The process of switching access points is called handoff. Handoff management is a key service in mobile networks, because providing seamless roaming in wireless networks is mandatory for supporting real-time applications in a mobile environment, such as VoIP, online games, and eConference. Security is another important issue in network communications, and to prevent possible attacks, authentication is required during the handoff process to guarantee the reliability of mobile clients and access points. In this paper, we propose a novel authentication scheme to achieve a smooth handoff in WiFi-based networks, which we refer to as TEASE. A tunnel is introduced to forward data packets between the new access point and the original reliable access point. The processing of a complete secure authentication and the transmitting of data between mobile terminals and their correspondence nodes can go on simultaneously. The security of handoff is achieved without increasing overhead to authentication servers, and handoff latency can be minimized to support seamless roaming. Simulation results show that our proposed scheme reduces significantly the communication interruption time and generates low packet loss ratio, and our method is suitable to be used for secure handoff in real-time applications.