Handoff in WLAN/cellular systems based on a hybrid of WLAN bandwidth and ad hoc relaying strategies
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Handoff in WLAN/cellular systems based on a hybrid of WLAN bandwidth and ad hoc relaying strategies M. Shiri1 · R. Berangi1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The seamless vertical handoff from a wireless local area network (WLAN) to a cellular system yet poses a big challenge. While serving by a WLAN, a mobile node (MN) may enter a region with a low data rate before completing a handoff towards a cellular network. To maintain quality of service, a large amount of WLAN bandwidth must be allocated to compensate for the weakness of MN link. However, this mechanism does not work properly in dense hotspots because of the lack of WLAN bandwidth. An alternative is to employ relay nodes (RN) to remain connected to the AP. This scheme also does not operate well in a low-density hotspot because the chance of finding a suitable RN is low. In this paper, a hybrid solution that uses both WLAN bandwidth and potential RNs is proposed. It uses the trade-off between the WLAN bandwidth and the potential RNs to reach an optimum handoff performance in terms of call dropping probability. Initially, the probability of call dropping in relay mode is theoretically evaluated and compared with the simulation results. Next, the proposed Hybrid approach is modelled by assuming 5% and 10% of nods as the relay nodes. The results show the proposed method can significantly reduce call dropping probability in both low and high-density hotspots when compared with a relay or bandwidth-based approach. It also reduces new call blocking probability of the bandwidth only but slightly worse than the relay only methods. Keywords Relay-assisted handoff · Bandwidth-assisted handoff · Call dropping probability · Call blocking probability · WLAN to cellular handoff
1 Introduction Recent years witnessed the growth of wireless local area network (WLAN) and its data rates [1]. The high data rate and the low price of service in WLAN have made it an attractive infrastructure for mobile nodes (MNs) [2]. However, WLAN suffers from limited coverage. A solution is to let WLAN interwork with the worldwide interoperability for microwave access (WiMAX) or the different types of cellular networks such as the universal mobile telecommunications service (UMTS) and the long term evolution (LTE). In the heterogeneous networks (HetNets), WLAN is an important complementary system for current 5G cellular networks [3]. Handoff plays the most important role in the integrity and stability of services in the HetNets. Accomplishing a
* R. Berangi [email protected] 1
Department of Computer Engineering, Iran University of Science and Technology, Tehran 16846‑13114, Iran
seamless handoff between wireless networks is a challenging issue [4]. During the accomplishment of a handoff from a cellular network to a WLAN, the MN is connected to the cellular network and it thoroughly receives service from the cellular network; therefore, this kind of handoff is less complicated. Furthermore, the handoff from the WLAN to the cellular network
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