Modeling and analyzing the cost of hierarchical mobile IP

Handoff latency affects the service quality of real-time applications. In this paper we develop an analytical model to analyze the Mobile IP Fast Authentication protocol (MIFA) and compare it to Hierarchical Mobile IP (HMIP). The study compares the signaling costs of the protocols as well as the overall load for packet forwarding. Our study shows that MIFA minimizes the packet delivery cost compared to HMIP. Additionally, MIFA is more efficient when the arrival rate of the packets increases. Thus MIFA outperforms HMIP with respect to signaling cost. From the performance point of view MIFA performs similar to HMIP when the domain consists of two hierarchy levels only, and outperform HMIP otherwise. However, MIFA does not require a hierarchical network architecture as HMIP does.

To solve the IP mobility problem, the use of multicast has been proposed in a number of different approaches, applying multicast in different characteristic ways. We provide a systematic discussion of fundamental options for multicast‐based mobility support and the definition and experimental performance evaluation of selected schemes. The discussion is based on an analysis of the architectural, performance‐related, and functional requirements. By using these requirements and selecting options regarding network architecture and multicast protocols, we identify promising combinations and derive four case studies for multicast‐based mobility in IP‐based cellular networks. These case studies include both the standard any‐source IP multicast model as well as non‐standard multicast models, which optimally utilize the underlying multicast. We describe network architecture and protocols as well as a flexible software environment that allows to easily implement these and other classes of mobility‐supporting multicast protocols.Multicast schemes enable a high degree of flexibility for mobility mechanisms in order to meet the service quality required by the applications with minimal protocol overhead. We evaluate this overhead using our software environment by implementing prototypes and quantifying handoff‐specific metrics, namely, handoff and paging latency, packet loss and duplication rates, as well as TCP goodput. The measurement results show that these multicast‐based schemes improve handoff performance for high mobility in comparison to the reference cases: basic and hierarchical Mobile IP. Comparing the multicast‐schemes among each other the performance for the evaluated metrics is very similar.As a result of the conceptual framework classification and our performance evaluations, we justify specific protocol mechanisms that utilize specific features of the multicast. Based on this justification, we advocate the usage of a source‐specific multicast service model for multicast‐based mobility support that adverts the weaknesses of the classical Internet any‐source multicast service model. Copyright © 2006 John Wiley & Sons, Ltd.

Ever-increasing demand of mobile Internet traffics makes mobile networks change from hierarchical architecture to flat architecture. Most of the current mobility protocols are based on a centralized mobility anchor, by which all the control and data traffics are processed. In the flat network architecture, however, the centralized mobility scheme has some limitations, which include unwanted traffic flowing into core network, service degradation by a point of failure, and increased operational costs, etc. In this paper, we propose the three distributed mobility control schemes for flat architecture of future mobile networks: Partially Distributed Mobility Control (PDMC), Data-driven Distributed Mobility Control (DDMC), and Signal-driven Distributed Mobility Control (SDMC). By numerical analysis, we compare the proposed distributed mobility schemes with the existing centralized mobility scheme using Proxy Mobile IPv6 (PMIP) in terms of binding update and packet delivery costs. From the results, it is shown that the three proposed distributed schemes give better performance than the existing centralized PMIP scheme, and the SDMC scheme provides the best performance among the three proposed distributed schemes.

To improve handoff performance of the network-based Proxy Mobile IPv6 (PMIPv6), two types of enhanced handoff schemes have been presented; fast handover for PMIPv6 (F PMIPv6) and route optimization handover (ROH). The F PMIPv6 is committed to reduce handoff latency and is efficient to perform handoff signaling. However, it causes high packet delivery cost from additional tunneling at the LMA. The ROH minimizes packet delivery cost by allowing direct route of MAG to-MAG but introduces high handoff signaling cost. Due to the tradeoff between handoff signaling and packet delivery cost, both schemes cannot guarantee a better performance for a diverse mobile environment where a mobile node (MN) has a different session arrival and mobility rate. Thus, we propose an adaptive PMIPv6 handoff (APHO) scheme to reduce the overall data overhead and improve the throughput over a wide range of session-to-mobility ratio (SMR). The APHO consists of mobility aware APHO (M-APHO) and session-aware S-APHO (S-APHO), which are determined by comparing the SMR and pre-defined threshold. By analyzing the performance of FHO, ROH, and APHO, we confirm that the APHO has a better performance than the other schemes over a wide range of SMR.

A variety of schemes for mobility are currently studied in ITU-T, 3GPP, IETF, and so on. The ITU-T (SG-19) considers Q.MMF, the 3GPP standardized IMS, the IETF currently uses mobile IP (MIP). For supporting mobility, there are many performance parameters, such as location registration delay, handover delay, packet delivery delay, signaling cost, location update cost, packet delivery cost. However the performance comparison of all existing schemes is not examined as yet. So, this paper investigates and compares the performance of MIPv6, IP2, Q.MMF, IMS to location registration. The time and cost of location registration are associated with the flow of messages between entities according to the procedure. We investigate the variation and performance comparison in the location registration time and cost using the performance metric

The convergence of heterogeneous wireless networks combines existing wireless networks. An effective combination of different wireless networks should enable them to complement each other and provide high-speed data rate, wide area coverage, and quality of service (QoS) guarantee. In Next Generation Wireless Systems (NGWS), seamless handoff between different wireless access networks plays a vital role. One of the major challenges for seamless mobility is the creation of a vertical handoff protocol. In this paper, the performance of vertical handoff is studied using the integration of third generation (3G) cellular and wireless local area networks (WLAN). The effect of application-based signal strength threshold (ASST) and path loss exponent on an adaptive lifetime-based vertical handoff (ALIVE-HO) strategy is studied in terms of number of handoffs, aggregated throughput, and packet delay. Therefore the vertical handoff performance can be optimized in wireless and mobile networks. The present work is done for different channel conditions as well as different mobility schemes.

Performance of two low latency handoff schemes in mobile Internet protocol (Mobile IP), pre-registration handoff and post-registration handoff are evaluated in terms of packet loss by means of Network Simulation (NS). We describe several handoff implementations over wireless access based on the IEEE 802.11 standard on an NS simulation.We compare the system performance of pre-registration handoff and post-registration handoff with the original regional registration mobile IP with respect to packet loss. To reduce the packet loss in both schemes, the buffer is needed to implement at each base station and the overlapping area of each base station is considered.We, moreover, study the influence of the signaling cost over the anchor Foreign Agent (aFA) for post-registration handoff and over the Gateway Foreign Agent (GFA) for pre-registration handoff when both schemes have been implemented with the regional registration mobile IP. The group of FAs under the aFA or under the GFA has been selected in order to consume the minimal network resource.Post-registration handoff scheme, however, may lead to excessive signaling cost to an aFA where numerous FAs establish the bi-directional edge tunnel (BET) with it. Therefore, a method to determine the optimal number of FAs performing BET with the aFA in post-registration handoff is proposed. It is based on an analytical model by minimizing the total location update, packet delivery and processing BET costs. We investigate the total signaling cost at the aFA in the post-registration handoff by the proposed analytical model and NS simulation.

Infectious agents are likely to be sensitive to climate change if their life cycle includes periods of exposure to ambient conditions. Several studies have attempted to attribute changes in patterns of infectious diseases to recent climate change, such as resurgent malaria in the East African Highlands and the northward expansion of tick-borne encephalitis and Lyme disease in Europe and Canada. However, debate continues over the relative importance of climate change compared to social, demographic and other factors. Methods for the detection and attribution of climate change impacts on human infectious diseases have not been clearly defined. There are several areas of contention in the literature on appropriate methods for the detection of climate change effects on infectious diseases, including the availability and appropriate use of climate data, identifying regions where changes are most likely to be observed and the biological importance of small temperature increases and threshold effects. Definitions and strategies for the detection and attribution of climate change impacts on human infectious diseases are discussed and compared to approaches to the detection and attribution of climate change impacts in other fields. ‘Consistency analysis’ is proposed as a feasible methodological approach to address research questions about the impact of recent climate change on infectious diseases.

In mobile Internet, the host grouping maintenance or the multicast delivery tree for multicasting algorithm becomes a major issues. In this paper, we explore the issues of mobile multicast scheme using mobile-IPv6. Specifically, we address operation scenarios when a mobile host is a source as well as a recipient of a given multicast operation using MLD (multicast listener discovery) scheme, and the proposed MLD-based multicasting protocol, MIP-MLD uses a smooth handoff technique to reduce the service disruption for the multicast session during the handoff. We compared our scheme to existing approaches by cost analysis model, and gained an improved performance in terms of the multicast delivery path.

An improved stochastic life-cycle cost analysis model for examining the impact of environmental policy instruments on construction equipment replacement

Previous research has demonstrated that fasting C-peptide (FCP) serves as a protective element against diabetic retinopathy. But the protective effect of elevated FCP levels against diabetic retinopathy (DR) remains uncertain when these levels exceed specific thresholds. This research aimed to investigate the intrinsic link between FCP concentration and DR in individuals with T2DM. A total of 1661 individuals diagnosed with type 2 diabetes participated in this observational analysis, where DR was assessed as the primary outcome and categorized according to FCP levels. Curve fitting analysis and two-part linear regression models were applied to assess the relationship between DR and FCP, and exploratory analysis was conducted to identify the threshold. Our study found a non-linear relationship between the two, as well as a threshold effect at an FCP of 4.11 ng/mL. Below the critical value, each 1 ng/mL increase in FCP levels was associated with a 24% lower risk of DR (OR: 0.74, 95% CI: 0.64-0.86). Above the cutoff, the relationship did not reach statistical significance (OR: 1.52, 95% CI: 0.87-2.66). There was a nonlinear relationship between FCP level and DR risk, which was negatively correlated at first but stabilized at a lower level when FCP>4.11 ng/mL.

Global urbanization has long been hampered by the “metrocentric priority” paradigm, with small towns—core hubs for urban–rural integration—severely undervalued in practical value. Amid China’s transition to high-quality urban–rural integration, unbalanced small town development has become a critical bottleneck for county-level factor flows, demanding systematic research to unlock their strategic value and resolve urban–rural dual predicaments. Existing studies suffer from scientific gaps including unidirectional linear cognition, insufficient complex system thinking, and weak interpretation of regional heterogeneity, remaining at the stage of static correlation description and failing to reveal the two-way reciprocal feedback logic between small towns and urban–rural integration. Meanwhile, the application of complex system theory in urban–rural research is still confined to theoretical narratives, which hinders the advancement of research from descriptive analysis to mechanism interpretation. Taking Henan Province (a typical agricultural and populous province reflecting China’s urban–rural development) as a case, this study builds a “local emergence–global synergy” framework based on complex system theory, establishes a dual indicator system for small towns’ multidimensional performance and county-level urban–rural integration, and integrates spatial statistical analysis, bidirectional regression and coupling coordination models to explore their cross-scale spatiotemporal evolution and reciprocal feedback during 2019–2023. Findings show the following: (1) The multidimensional performance of small towns presents a pattern characterized by polarized expansion of high-value regions and overall improvement of low-value regions, while county-level urban–rural integration evolves into a polycentric structure featured by central dominance and southern growth. (2) There is a significant two-way asymmetric relationship between small towns’ multidimensional performance and county-level urban–rural integration: the positive effect is significantly stronger than the reverse effect, and both direct impacts are significantly weakened after introducing economic variables, indicating that economic development serves as a key transmission channel. (3) The coupling mechanism presents three evolutionary paths with pronounced core–periphery spatial heterogeneity. Grounded in complex system theory, this study constructs a systemic analytical framework of “local emergence of small-town subsystems and global synergy of county-level systems”, verifies the core proposition of two-way interactions between subsystems and the overall system in the urban–rural complex giant system, and enriches the localized application of complex system theory and the urban–rural continuum theory in traditional agricultural regions of China. This study provides a foundational empirical paradigm for the in-depth exploration of nonlinear characteristics and threshold effects in future research. It offers theoretical support for policy formulation of county-level urban–rural integration in traditional agricultural regions of China, and it provides Chinese experiences for the Global South with similar contexts to explore inclusive urbanization pathways, promoting cross-cultural dialogue and practical transformation of urban–rural integration theory.

The paper introduces proactive integrated handoff management (IHM) scheme in cognitive radio mobile ad hoc networks (CR-MANETs) through an established route. This scheme considers the primary user (PU) activity, secondary user (SU) mobility and channel heterogeneity in the spectrum handoff decision. To reduce the handoff delay, handoff thresholds are used. When the spectrum handoff cannot be done due to the SU's mobility, a local flow handoff (LFH) is performed to find a node in the vicinity of a potential link breakage where the data flow is transferred to the node. The proposed proactive IHM scheme predicts the cognitive link availability that considers the interference to PUs to estimate the maximum link availability time. The availability time is then used in the channel allocation scheme. The results emphasized on improvement of the route maintenance probability using LFH. It is also verified that the number of handoff needed is significantly decreased using the proposed proactive IHM scheme.

In this paper, Proactive Unified Spectrum Handoff (PUSH) scheme in cognitive radio mobile ad hoc networks (CR-MANETs) through an established route is considered in which the channel availability depends on the Primary User's (PU's) activity, secondary user's (SU's) mobility, and the channel heterogeneity. First, an analytical model for Unified Spectrum Handoff (USH) scheme is introduced in which the SUs will move to another unused spectrum band, giving priority to a PU. Then, the PUSH method is proposed in which a handoff threshold is used to initiate the handoff proactively. When a channel handoff cannot be performed due to the SU's mobility, a local flow handoff (LFH) is performed. The proposed PUSH algorithm uses the cognitive link availability prediction while considering the PU interference boundary to estimate the maximum link accessibility period. Based on the analytical model, the channel heterogeneity and the SU's mobility affected the performance of the handoff management method rather than the PU's activity. Both the simulation and analytical results demonstrated an improvement of route maintenance probability based on the LFH and cognitive link availability prediction mechanisms in PUSH.

Healthcare facilities require comprehensive maintenance management strategies to ensure optimal service delivery and operational efficiency. This study developed a life cycle cost analysis (LCCA) model to improve maintenance management and availability performance of mortuary buildings, using Musoma Municipal Council Hospital as a case study. A mixed-methods research approach was adopted, involving comprehensive field observations, structured interviews, and systematic surveys with 36 participants representing diverse stakeholders, including engineers, administrators, technicians, mortuary staff, and healthcare professionals. Twelve technical factors influencing maintenance costs were systematically analysed using the Relative Importance Index (RII) methodology to establish priority rankings based on professional expertise and operational experience. The analysis revealed that electrical systems' reliability and backup power emerged as the most critical factor (RII = 0.931), followed by environmental control for chemical storage (RII = 0.923), and infection control and biosafety features (RII = 0.915). A robust multiple regression model was subsequently formulated using the seven highest-ranked factors, producing strong predictive outcomes with R² = 0.780, indicating that 78% of the variance in availability performance could be explained by the identified technical factors. The resulting prediction equation: Y = 0.01 + 0.02X₁ − 0.11X₂ + 0.032X₃ + 0.08X₄ + 0.05X₅ + 0.03X₆ + 0.09X₇ demonstrated statistical significance (F = 10.327, p < 0.001), where X₁ to X₇ represent the prioritized technical components. Comprehensive validation over an eight-month period confirmed the model's reliability and practical applicability, with availability performance demonstrating significant improvement from 20% classified as "Very Severe" in January to 97% classified as "Very Good" in May. The study contributes to the limited body of knowledge on specialised healthcare facility maintenance management and provides hospital administrators with evidence-based tools for strategic decision-making, preventive maintenance planning, cost optimisation, and sustainable mortuary service delivery.