RSS based Vertical Handoff algorithms for Heterogeneous wireless networks - A Review
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paper_title: Performance evaluation framework for vertical handoff algorithms in heterogeneous networks

paper_content:

The next generation (4G) wireless network is envisioned as a convergence of different wireless access technologies providing the user with the best anywhere anytime connection and improving the system resource utilization. The integration of wireless local area network (WLAN) hotspots and the third generation (3G) cellular network has recently received much attention. While the 3G-network can provide global coverage with a low data-rate service, the WLAN can provide a high data-rate service within the hotspots. Although increasing the underlay network utilization is expected to increase the user available bandwidth, it may violate the quality-of-service (QoS) requirements of active real-time applications. Hence, achieving seamless handoff between different wireless technologies, known as vertical handoff (VHO), is a major challenge for 4G-system implementation. Several factors, such as application QoS requirements and handoff delay, should be considered to realize an application transparent handoff. We present a novel framework to evaluate the impact of VHO algorithm design on system resource utilization and user perceived QoS. We used this framework to compare the performance of two different VHO algorithms. The results show a very good match between simulation and analytical results. In addition, it clarifies the tradeoff between achieving high resource utilization and satisfying user QoS expectations.
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paper_title: A Traveling Distance Prediction Based Method to Minimize Unnecessary Handovers from Cellular Networks to WLANs

paper_content:

We propose a handover decision method based on the prediction of traveling distance within an IEEE 802.11 wireless local area network (WLAN) cell. The method uses two thresholds which are calculated by the mobile terminal (MT) as it enters the WLAN cell. The predicted traveling distance is compared against these thresholds to make a handover decision in order to minimize the probability of handover failures or unnecessary handovers from a cellular network to a WLAN. Our analysis shows that the proposed method successfully keeps the number of failed or unnecessary handovers low.
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Title: RSS based Vertical Handoff algorithms for Heterogeneous wireless networks - A Review

Section 1: INTRODUCTION
Description 1: This section introduces the concept of vertical handoff in heterogeneous wireless networks, emphasizing the significance of RSS based algorithms and the challenges associated with vertical handoff decisions.

Section 2: RSS BASED VHD ALGORITHMS
Description 2: This section details the basics of RSS based VHD (Vertical Handoff) algorithms and introduces three specific algorithms explored in this paper.

Section 3: ALIVE-HO (adaptive lifetime based vertical handoff)
Description 3: This section elaborates on the ALIVE-HO algorithm, its operational methodology, and the scenarios in which it is applied, including its advantages and limitations.

Section 4: Algorithm on Adaptive RSS Threshold
Description 4: This section discusses the algorithm proposed by Mohanty and Akyildiz, focusing on how it adapts the RSS threshold dynamically to reduce handoff failures and unnecessary handovers between WLAN and 3G networks.

Section 5: A Traveling Distance Prediction Based Method
Description 5: This section explains the traveling distance prediction-based method developed by Yan et al., which aims to minimize unnecessary handovers by considering the expected time a mobile terminal will spend within a WLAN cell.

Section 6: CONCLUSION
Description 6: This section provides a summary of the comparative analysis of the three RSS based vertical handoff algorithms, highlighting their respective strengths and weaknesses.

Section 7: FUTURE DIRECTIONS
Description 7: This section suggests potential future improvements to the discussed algorithms, including periodic sampling of RSS and refining estimations to enhance performance.