A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Handoff at the link layer 2 (L2) consists of three phases: scanning, authentication, and reassociation. Among the three phases, scanning is dominant in terms of time delay. Thus, in this paper, we propose an improved scanning mechanism to minimize the disconnected time while the wireless station (STA) changes the associated access points (APs). According to IEEE 802.11 standard, the STA has to scan all channels in the scanning phase. In this paper, based on the neighbor graph (NG), we introduce a selective channel scanning method for fast handoff in which the STA scans only channels selected by the NG. Experimental results show that the proposed method reduces the scanning delay drastically. <s> BIB001 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> With the growth of IEEE 802.11-based wireless LANs, VoIP and similar applications are now commonly used over wireless networks. Mobile station performs a handoff whenever it moves out of the range of one access point (AP) and tries to connect to a different one. This takes a few hundred milliseconds, causing interruptions in VoIP sessions. We developed a new handoff procedure which reduces the MAC layer handoff latency, in most cases, to a level where VoIP communication becomes seamless. This new handoff procedure reduces the discovery phase using a selective scanning algorithm and a caching mechanism. <s> BIB002 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> The IEEE 802.11 standard has enabled low-cost and effective wireless local area network (WLAN) services. It is widely believed that WLANs will become a major portion of the fourth-generation cellular system. The seamless handoff problem in WLANs is a very important design issue to support the new astounding and amazing applications in WLANs, particularly for a user in a mobile vehicle. The entire delay time of a handoff is divided into probe, authentication, and reassociation delay times. Because the probe delay occupies most of the handoff delay time, efforts have mainly focused on reducing the probe delay to develop faster handoff schemes. This paper presents a new fast handoff scheme (i.e., the DeuceScan scheme) to further reduce the probe delay for IEEE-802.11-based WLANs. The proposed scheme can be useful to improve wireless communication qualities on vehicles. A spatiotemporal approach is developed in this paper to utilize a spatiotemporal graph to provide spatiotemporal information for making accurate handoff decisions by correctly searching for the next access point. The DeuceScan scheme is a prescan approach that efficiently reduces the layer-2 handoff latency. Two factors of stable signal strength and variable signal strength are used in our developed DeuceScan scheme. Finally, simulation results illustrate the performance achievements of the DeuceScan scheme in reducing handoff delay time and packet loss rate and improving link quality. <s> BIB003 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> This paper proposes a novel IPv6 address autoconfiguration that works with multiple types of mobile networks, such as MANET, NEMO, MANEMO, as well as regular IPv6 networks. Our proposed algorithm assigns unique addresses to mobile devices without performing duplicate address detection. As a result, an address autoconfiguration can be done rapidly. This is suitable for system that requires dynamic movement and quick handover such as a disaster relief system or car-car communication. <s> BIB004 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Proxy Mobile IPv6 (PMIPv6), a network-based IP mobility solution, is a promising approach for mobility management in all-IP wireless networks. How to enhance its handoff-related performance, such as handoff delay and signaling cost, is an important issue. Current solutions rely on approaches such as fast handoff, routing optimization and paging extension. However, the case of many correlated Mobile Nodes (MNs) moving together and taking handoffs at the same time has not been considered. In this paper, we propose a group-based handoff scheme for correlated MNs to enhance the performance of PMIPv6. We first propose a correlated MNs detection algorithm to detect MNs as groups. Based on this algorithm, we propose a groupbased handoff procedure, and discuss its benefits and limitations. Furthermore, we evaluate the performance of PMIPv6 and our proposal through the analysis and simulation. The results show that the proposed scheme is very efficient in reducing both the handoff delay and signaling cost. <s> BIB005 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> IP based Wireless Sensor Networks (IP-WSN) are gaining importance for its broad range of applications in health-care, home automation, environmental monitoring, security & safety and industrial automation. In all of these applications mobility in sensor network with special attention to energy efficiency is a major issue to be addressed. Host based mobility management protocol is inherently unsuitable for energy inefficient IPWSN. So network-based mobility management protocol can be an alternative to the mobility supported IP-WSN. In this paper we propose a mobility supported IP-WSN protocol based on PMIPv6 called Sensor Proxy Mobile IPv6 (SPMIPv6). We present its architecture, message formats and also analyze its performance considering signaling cost and mobility cost. Our analyses show that the proposed scheme reduces the signaling cost by 67% and 60% as well as reduces mobility cost by 55% and 60% with comparison to MIPv6 and PMIPv6 respectively. <s> BIB006 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Group mobility in wireless sensor network (WSN) is of particular importance in many practical application scenarios. In this paper, the group mobility management in IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) based WSN is considered and the application of network mobility (NEMO) protocol to support group mobility in WSN is discussed. A new network architecture supporting the integration of NEMO and 6LoWPAN-based WSN is proposed, the group mobility management mechanism and the corresponding signaling flow are discussed. Simulation results demonstrate that comparing to MIPv6, the application of NEMO protocol in 6LoWPAN reduces both the handoff latency and the energy consumption of sensor node. <s> BIB007 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> This document specifies the usage of Fast Mobile IPv6 (FMIPv6) when ::: Proxy Mobile IPv6 is used as the mobility management protocol. ::: Necessary extensions are specified for FMIPv6 to support the scenario ::: when the mobile node does not have IP mobility functionality and hence ::: is not involved with either MIPv6 or FMIPv6 operations. <s> BIB008 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> In this paper, we focus on a scheme that supports mobility for IPv6 over Low power Wireless Personal Area Network (6LoWPAN) sensor nodes. We define a protocol for 6LoWPAN mobile sensor node, named 6LoMSN, based on Proxy Mobile IPv6 (PMIPv6). The conventional PMIPv6 standard supports only single-hop networks and cannot be applied to multihop-based 6LoWPAN. It does not support the mobility of 6LoMSNs and 6LoWPAN gateways, named 6LoGW, cannot detect the PAN attachment of the 6LoMSN. Therefore, we define the movement notification of a 6LoMSN in order to support its mobility in multihop-based 6LoWPAN environments. The attachment of 6LoMSNs reduces signaling costs over the wireless link by using router solicitation (RS) and router advertisement (RA) messages. Performance results show that our proposed scheme can minimize the total signaling costs and handoff latency. Additionally, we present the design and implementation of the 6LoMSN mobility based on PMIPv6 for a healthcare system. According to the experimental results, the 6LoMSN of the proposed PMIPv6-based 6LoWPAN can be expected to use more of the battery lifetime. We also verify that the 6LoMSN can maintain connectivity, even though it has the freedom of being able to move between PANs without a mobility protocol stack. <s> BIB009 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Next Generation Networks (NGN) both static and mobile are expected to be fully Internet Protocol Version 6 (IPv6) based. Mobility in IPv6 (MIPv6) network was designed to provide Internet services to end users at anytime and anywhere. However, MIPv6 is not widely deployed yet due to handoff latency and other limitations leading to packet loss and Quality of Service (QoS) degradation for real time applications such as audio and video streaming. MIPv6 handoff latency can be categorized into layer 2 (L2) and layer 3 (L3) delays that includes link layer establishment delay, movement detection delay, address configuration delay and binding update or registration delay. Movement detection delay and address configuration including Duplicate Address Detection (DAD) in L2 and L3 respectively consume the highest time of the total delay. In order to reduce these handoff latencies, two solutions are proposed to focus all the delays both in L2 and L3. The first solution is the fuzzy logic technique based network awareness to reduce movement detection delay especially the scanning time in L2 in heterogeneous networks. The second solution is Parallel DAD (PDAD) to reduce address configuration time in L3. Both solutions benchmarked with OMNeT++ simulator show improvements over standard MIPv6 networks. The handoff latency reduced more than 50% and packet loss improved around 55% in L2. Moreover, in L3 the handoff latency reduction accounts for 70% and packet loss improved approximately 60%. The handoff latency is reduced from 1300 ms to 500 ms applying fuzzy logic technique at L2 and PDAD mechanism in L3 leading to overall delay reduction of 60%. <s> BIB010 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> In Proxy Mobile IPv6 (PMIPv6), any involvement by the Mobile Node (MN) is not required, so that any tunneling overhead can be removed from over-the-air. However, during the PMIPv6 handover process, there still exists a period when the MN is unable to send or receive packets because of PMIPv6 protocol operations, suffering from handover latency and data loss. Thus, to reduce the handover latency and data loss in PMIPv6, Fast Handover for PMIPv6 (PFMIPv6) is being standardized in the IETF. Nevertheless, PFMIPv6 has a few weaknesses: (1) handover initiation can be false, resulting in the PFMIPv6 handover process done so far becoming unnecessary. (2) Extra signaling is introduced in setting up an IP-in-IP tunnel between the serving and the new Mobile Access Gateways (MAGs). Therefore, in this paper, we present our study on the protocol overhead and performance aspects of PFMIPv6 in comparison with PMIPv6. We quantify the signaling overhead and the enhanced handover latency and data loss by conducting a thorough analysis of the performance aspects. The analysis is very meaningful to obtain important insights on how PFMIPv6 improves the handover performance over PMIPv6, especially in a highway vehicular traffic scenario where Base Stations (BSs)/Access Points (APs) can be placed in one dimensional space and MN's movements are quasi one-dimensional, so that the degree of certainty for an anticipated handover is increased. Further, our analytical study is verified by simulation results. <s> BIB011 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> The IPv6 over low power wireless personal area network (6LoWPAN) has attracted lots of attention recently because it can be used for the communications of Internet of things. In this paper, the concept of group-based network roaming in proxy mobile IPv6 (PMIPv6) domain is considered in the 6LoWPAN-based wireless body area networks. PMIPv6 is a standard to manage the network-based mobility in all-IP wireless network. However, it does not perform well in group-based body area networks. To further reduce the handoff delay and signaling cost, an enhanced group mobility scheme is proposed in this paper to reduce the number of control messages, including router solicitation and router advertisement messages as opposed to the group-based PMIPv6 protocol. Simulation results illustrate that the proposed handoff scheme can reduce the handoff delay and signaling cost. The packet loss ratio and the overhead can also be reduced. <s> BIB012 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Recently it has been observed that internet of things (IoT) technology is being introduced in medical environment to achieve a global connectivity with the patient, sensors and everything around it. The main goal of this global connectivity is to provide a context awareness to make the patient's life easier and the clinical process more effective. IPv6, the new Internet Protocol has made every grain of sand on earth addressable and thus emergence of a new technology called IoT. IoT is simply a machine to machine M2M communication and Sensor nodes are proved to be best suited for this new technology. IPv6 over low power wireless personal area network (6LoWPAN) has attracted lots of attention recently as it can be used for communication of IoT. This paper provides a framework for medical environment, for reducing handoff (HO) latency and signaling overhead while the patient is on the move inside the hospital premises and further it can be applied to other domains also where can be applicable. Sensor nodes can be used for collecting the particular parameters of human body which constitutes wireless body area network (WBAN). The proposed framework surely reduces the signaling overhead and thus the HO latency and hence there will be an improvement in QoS. <s> BIB013 </s> A Review of Network Based Mobility Management Schemes, WSN Mobility in 6LoWPAN Domain and Open Challenges <s> Open Challenges <s> Automotive telematics has become an important technology for high-speed rail systems, which are being increasingly popular in this era of green technology. As the train speed increases, however, communications between the train and infrastructure encounter major difficulties of maintaining high quality communication. Handovers on high-speed trains occur more frequently and have shorter permissible handling times than for traditional vehicles. In this paper, the proposed 2MR network mobility scheme takes advantage of the physical size of high-speed trains to deploy two mobile routers (MRs) in the first and last carriages. This scheme provides a protocol to allow the two MRs to cooperate with a wireless network infrastructure in facilitating seamless handovers. Our simulation results demonstrate that compared to the traditional single MR schemes, the 2MR scheme noticeably improves the communication quality during handover by significantly reducing handover latency as well as packet loss for high-speed trains. <s> BIB014
From the literature survey, we conclude that lot of work has been carried out on IP mobility management schemes to provide seamless handover to MN. Some of the existing methods are host based while others are network based. Network based mobility protocols found to be very useful in 6LoWPAN mobility. Such networks are composed of devices with limited energy resources, memory and computational power. Recently, the research community enabled IPv6 connectivity in those networks by the means of an adaptation layer BIB006 BIB009 and researchers have done extensive work in this area (see figures 2 and 3). The focus of the research is to reduce signaling cost, packet loss and particularly HO latency. HO latency is caused by L2 and L3 handoffs. Channel scanning, authentication and association delays contribute L2 delays while as movement detection (mdd), CoA, duplicate address detection delay (dad) and registration delay contribute L3 delays BIB010 . The most time consuming delay is channel scanning. Approaches used in BIB001 BIB002  BIB003 have made some improvements in reducing L2 delay. In  , Pre-registration is used to reduce HO delay while BIB002 used caching AP strategy for the same. The group based protocols in BIB007 BIB005 reach the goal of reducing the signaling cost due to carrying of binding information by the newly attaching nodes in WBAN  . But sensors in WBAN attach to new link at the same time. Therefore in BIB012 , one control message (RA and RS) to carry the whole body sensor's information was used to reduce the signaling cost. In  , FPMIPv6 was further used to reduce the signaling cost in sensor networks. Therefore we realize that Healthcare is also one of the research fields, growing rapidly on the basis of these 6LoWPAN WSN. Many healthcare applications use the existing mobility management protocols. Although these schemes are providing acceptable results but still suffer from few shortcomings: In this article we take the hospital wireless sensor network (HWSN) as case study. Continuous Patient's health monitoring in HWSN is very essential. The patients are autonomous and mobile. To support mobility in HWSN, the signaling messages (RA and multicast messages) used for registration process should be made few to enhance the SN's life, deployed on patient's body. HWSN is controlled network and mobile node (SN) is well aware of the infrastructure. So the continuous exchange of messages between mobile SN and AP to check the signal strength can be avoided which saves life of battery operated devices and enhances their mobility. Also multi-hop communication adds up extra signaling overhead between SN and AP which also leads to drain of SN's battery. Single-hop communication can be achieved by deploying extra APs, although it will increase expenditure but provides Signaling cost effective and seamless mobility. In HWSN, sensors on patient's body generate critical data including patient's body parameters such as Pulse rate, ECG, Sugar Level, Body Temperature, Blood pressure etc. This data is time critical and should be transmitted to Hospital Monitoring Station without any packet loss. An expert sitting at monitoring station has to give immediate advice by interpreting the received data. Any loss in this data can put patient's life in danger and it is not acceptable BIB013 . Existing mobility schemes suffer from packet loss during HO in HWSN and results in loss of data. The packet loss is due to the termination of connection during HO. Attempts should be made to control the packet loss during HO by buffering the packets either at previous AP (The current home of MN) or at new AP (where the MN intends to move) and deliver the buffered packets to the MN after the HO is completed. The best suitable protocol to monitor the patient's mobility (patient moves in different departments inside the hospital under different MAG domains) in hospital scenario would be Fast Handovers for PMIPv6 (FHPMIPv6) BIB008 . FHPMIPv6 buffers the data packets either at Previous Mobile Access Gateway (pMAG) or New MAG (nMAG) and these packets are delivered to the Mobile Node (MN) after the HO Process is over. In this way the critical data can be saved from being lost and QoS improved in HWSN mobility scenario. Signaling cost is another issue which includes RtSol, RtAdv, BU and BAck messages that can be reduced by making one (RtSol. and RtAdv.) message for all the body sensors. HO latency includes movement detection delay (mdd), BU delay, duplicate address detection delay (dadd) and address configuration dalay (acd) which can be further reduced by omitting acd due to the auto address configuration property of IPv6 BIB004 . Fast Handovers for PMIPv6 (FHPMIPv6) has been standardized by the IETF in RFC 5949 BIB008 and lot of work is being carried out using this protocol to avoid packet loss during HO process. In BIB011 FHPMIPv6 used for highway vehicular traffic scenario. In BIB014 same protocol was used to provide seamless handover in high speed trains and produced better results than PMIPv6. To the best of our knowledge FHPMIPv6 has not been used for monitoring patient's mobility in HWSN so far. Therefore using FHMIPv6 will definitely make some improvements in the Healthcare mobility monitoring as it has shown good results in other critical areas mentioned above.