Mobile IP has been developed to handle mobility of Internet hosts at the network layer. Mobile IP, however, suffers from a number of drawbacks such as requirement of infrastructure change, high handover latency, high packet loss rate, and conflict with network security solutions. In this paper, we describe and evaluate the performance of SIGMA, a Seamless IP diversity based Generalized Mobility Architecture. SIGMA utilizes multihoming to achieve a seamless handover of a mobile host, and is designed to solve many of the drawbacks of Mobile IP, including requirement for changes in infrastructure. We first evaluate the signaling cost of SIGMA and compare with that of Hierarchical Mobile IPv6 (an enhancement of Mobile IP) by analytical modeling, followed by comparison of handover performance of SIGMA and Mobile IPv6 enhancements. Criteria for performance evaluation include handover latency, packet loss, throughput, and network friendliness. Our results indicate that in most cases SIGMA has a lower signaling cost than Hierarchical Mobile IPv6. Moreover, for a typical network configuration, SIGMA has a higher handover performance over Mobile IP.

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Abstract-Domain Name System (DNS) can be deployed in the network as a Location Manager (LM) for mobility management. The suitability of Domain Name System (DNS) as an LM can be measured by how successfully it can serve to locate a mobile host. In this paper, we developed an analytical model to measure the performance of DNS as LM for mobility management techniques with IP Diversity support based on success rate which takes into account the radius of the subnet, the residence time of MH in that subnet, latency in the network and the overlapping distance of two neighboring subnets. Our analysis shows that for a reasonable overlapping distance, DNS can serve as an LM with very high success rate even under some high network latency.

Abstract-TCP has been found to perform poorly in the presence of spurious timeouts (ST) caused by delay spikes which are especially more frequent in today's wireless mobile networks than in traditional wired network. Because STs do not frequently occur in wired networks, and are generally considered to represent a transient state, previous research did not consider the effects of ST on the steady state performance of TCP. However, ST is more frequent in wireless mobile environments, and must be considered explicitly to accurately model the steady state sending rate and throughput of TCP. In this paper, we propose an analytical model for the sending rate and throughput of TCP Reno as a function of packet error rate and characteristics of spurious timeouts. The accuracy of the proposed model has been validated against simulation results. The accuracy of the model has also been compared with previous models, and has been found to be more accurate than previous models in the presence of spurious timeouts.

Abstract-The Stream Control Transmission Protocol (SCTP)is being standardized by IETF as a reliable transport protocol to address a number of limitations of TCP. Due to its attractive features such as multi-streaming and multi-homing, SCTP has received much attention from the research community and industry. This paper serves as a tutorial by introducing the main features of SCTP, and discussing the state of the art in SCTP research activities. We also provide a survey on the available products which implement SCTP. Finally, the challenges faced by SCTP research community are identified with a view to stimulating further research.

Mobile IP has been developed by IETF to handle mobility of Internet hosts at the network layer. Mobile IP suffers from a number of drawbacks, including low survivability due to single-point failure of Home Agents. Recently, Seamless IP diversity based Generalized Mobility Architecture (SIGMA) was proposed to support low latency, low packet loss mobility of IP hosts. In this paper, we show that the location management scheme used in SIGMA enhances the survivability of the SIGMA-based mobile network. We develop an analytical model to evaluate and compare the survivability of SIGMA with that of Mobile IP. Numerical results show the improvement in system response time and service blocking probability of SIGMA over Mobile IP in the presence of hardware failures and Distributed Denial of Service (DDoS) attacks.

Background Schizophrenia is a complex mental disease whose cause is still unknown. Neuronal nicotinic acetylcholine receptors (nAChRs) have been implicated in various neurological disorders, including schizophrenia. The previous reports have shown that CHRNA polymorphisms were involved in schizophrenia. This study is to explore the potential association between CHRNA5 (OMIM#118505) polymorphisms and schizophrenia susceptibility in a Chinese population. Methods and Results A case–control study was conducted with 384 schizophrenia patients and 687 controls. We genotyped eight single nucleotide polymorphisms (SNPs) distributed in CHRNA5. Regulome DB, HaploReg, and GTEx databases were used to calculate possible functional effects of the polymorphisms. The χ2 test, genetic model analysis, and haplotype analysis were involved in assessing genetic association between variants and schizophrenia risk. The results exhibited that rs17486278 (NC_000015.10:g.78575140A>C) was associated with a decreased risk of schizophrenia on the basis of the recessive model (adjusted OR = 0.37, 95%CI: 0.15–0.93) in females. Moreover, we found that the four variants rs588765, rs6495306, rs680244, rs692780 were extremely significant after being stratified by ≥45 years. Conclusions Overall, our findings supported that the potential association existed between CHRNA5 polymorphisms and schizophrenia susceptibility in a Chinese population. But, large sample validation is needed to enhance the accuracy of our results.

Abstract-Wireless networks are becoming more heterogeneous; different classes of networks co-exist and users want to connect to any available network, anytime. So, it is important to have a mobility management scheme that can manage handoff for both inter-class and intra-class mobility so that the users can connect to and roam between any network. We propose an end-toend mobility management scheme, Multi-class SIGMA (mSIGMA), that performs soft handoff for inter-class and intra-class mobility in wireless network. Our analysis shows mSIGMA performs seamless handoff across networks with low delay and packet loss. We have also shown though experimental analysis that mSIGMA is implementable with existing networking technologies and can perform handoff efficiently.