萬代 雅希

Multi-view video consists of multiple views which are taken by multiple cameras from different positions and angles. It allows the users to freely change their viewpoints. Typical applications of multi-view video include Free Viewpoint TV, remote medical surgery, wireless multimedia sensor networks and so on. However, the traffic of multi-view video is also several times larger than traditional multimedia, which brings much more increment in the bandwidth requirement. To overcome this problem, Simulcast and MVC (Multi-view Video Coding) can be used to decrease the traffic for multi-view video. However, although Simulcast removes redundant information within each view, it still contains a large amount of inter-view redundant information. MVC further removes the correlation between the views, but all the views should be encoded and transmitted. So the bit-rates are still too high in these schemes. In this paper, in order to reduce the bit-rate for multi-view video transmission, we analyze the user's motion which is classified into random access model and successive motion model. We find that in the successive motion model only part of frames are possible to be displayed in a period of time. According to the analytical result, we propose a user dependent system to decrease the bit-rate of multi-view video transmission. The proposed system only encodes and transmits those frames that are possible to be displayed according to the user's motion. Further, in order to support the proposed system, we also propose a prediction structure as a substitute of the prediction structure in MVC. Performance evaluation proves that the proposed system reduces the average bit-rate for the transmission of multi-view video and is to be more effective when the number of views is large.

The traffic of multi-view video is several times larger than traditional multimedia, which brings much more increment in the bandwidth requirement. To overcome this problem, Simulcast and MVC (Multi-view Video Coding) can be used to decrease the traffic for multi-view video. However, although Simulcast removes redundant information within each view, it still contains a large amount of inter-view redundant information. MVC further removes the correlation between the views, but all the views should be encoded and transmitted. So the bit-rates are still too high in these schemes. In this paper, in order to reduce the bit-rate for multi-view video transmission, we analyze the user's motion which is classified into random access model and successive motion model. We find that in the successive motion model only part of frames are possible to be displayed in a period of time. According to the analytical result, we propose a user dependent scheme to decrease the bit-rate of multi-view video transmission. The proposed scheme only encodes and transmits those frames that are possible to be displayed according to the user's motion. Further, in order to support the proposed scheme, we also propose a prediction structure as a substitute of the prediction structure in MVC. Performance evaluation proves that this proposed scheme reduces the average bit-rate for the transmission of multi-view video. © 2011 IEEE.

In this paper, we propose and implement a cross layer protocol for ad hoc networks using directional antennas. In the proposed protocol called RSSI-based MAC and routing protocol using directional antennas (RMRP), RSSI is used for computing the direction of the receiver and also used for controlling backoff time. Moreover, the backoff time is weighted according to number of hops from a source node. In addition, simple routing functions are introduced in the proposed RMRP. We implement the proposed RMRP on a testbed with the electronically steerable passive array radiator (ESPAR) antenna and IEEE 802.15.4. From some experimental results, we confirm some throughput improvement and show the effectiveness of the proposed RMRP. Especially, the proposed RMRP can achieve about 2.1 times higher throughput than a conventional random backoff protocol in a multi-hop communication scenario.

Recently, multi-view video that is taken by multiple cameras from different positions and angles to provide the real world experience has attracted more attentions. Its typical applications include Free Viewpoint TV, remote medical surgery, wireless multimedia sensor networks and so on. The size of multi-view video is several times bigger than traditional multimedia, which brings much more increment in the bandwidth requirement. Compression technologies, such as MPEG and MVC, can greatly decrease the size of multi-view video. However, as just one view is displayed at a specific time, even with MVC bit-rate of multi-view video is still high. In this paper, we researched the switch models of the multi-view video applications and proposed a user-driven multi-view video streaming system which can significantly decrease the bandwidth requirement and provide better user experience. In the proposed system, only those frames that are possible to be displayed are encoded and transmitted and the data are transported by different protocols to decrease the effect of the network congestion. In order to support this solution, we also improved the prediction structure as a substitute of the prediction structure in MVC. Evaluation proves that this proposed solution is great helpful to reduce the average bit-rate and the bandwidth requirement for the transmission of multi-view video. ©2010 IEEE.

This paper addresses a transmission scheduling for wireless multi-hop network employing physical layer wireless network coding (PL-WNC). With PL-WNC, two distant nodes first transmit packets to an intermediate relay simultaneously, which then amplifies and forwards the received signal. The destination nodes decode the desired signals by using the a priori information which are their own packets or packets overheard from the other nodes. The achievable performance of PL-WNC depends not only on traffic pattern within a network but also on the probability for each destination node to have the a priori information for decoding the desired information. In this paper, we introduce a scheduling strategy for PL-WNC, which decides source-destination pairs of PL-WNC, taking account of traffic pattern as well as overhearing probability among nodes. The selected sources transmit packets only when the destinations are expected to have the a priori information with high probability. We define a parameter for each source node to decide whether it should transmit a packet when scheduled, and investigate its impact on the achievable throughput. Our simulation results show that our proposed scheduling significantly improves throughput of PL-WNC.

Due to the recent development in micro mechanics, electronics and wireless communication technologies, Multi-Robot Sensor Network (MRSN) becomes a hot issue for many robotic applications. In MRSN, from a viewpoint of sensor network communication, each robot senses data and transmits it to the adjacent robot to collect all data at the sink in a multi-hop manner. According to applications, delay taken to collect data, energy consumed by each robot for communication and data accuracy of the collected data are critical concerns. However, these three are in trade-off one another. In this paper, we discuss the tradeoffs among communication delay, energy consumption, and data accuracy of data collection in multi-robots systems. We focus on the data aggregation technique, which suppresses number of data to be transmitted. First, we analyze with Markovian chain the three categories of data aggregations, i.e., non-aggregation (conventional), full aggregation, and partial aggregation. The partial aggregation proposed by us in the previous paper can control aggregation by a simple parameter set called random pushing rate vector. The analytical result shows that, conventional method suffers large energy consumption with the highest accuracy, while full aggregation suffers long transmission delay with the least accuracy. We also find that the partial aggregation can trade off energy, delay and accuracy. Then, we discuss the tradeoffs among data accuracy, transmission delay and energy consumption with different significance according to different applications by proposing tradeoff index (TOI). Based on the TOI we discuss the several applications of MRSN with different significance of delay, energy and accuracy. From the results, we find that non-aggregation has the best TOI for low data generation rate, that the partial aggregation does for moderate generation rate, and that the full aggregation does for large data generation rate. The obtained results can provide the metric of aggregation for different applications. © 2010 IEEE.

Due to the Recent development in wireless technology, wireless sensor networks attract researchers' attention because of their applicability in many fields for effective collection of sensing data with low cost. Wireless sensor networks have many applications; some of the applications are military application, environmental application and flood detection. For example, in an environmental application for forest fire detection, the sensor nodes sense the fire information, then transmit or relay the information to base station in a multi-hop way. In wireless sensor networks, energy saving is critical issue as sensor nodes are battery-powered. Here we propose, partial data aggregation as one of the energy saving technique. In this paper, we analyze the tradeoffs among communication delay, energy consumption, and data accuracy of the partial data aggregation technique and discuss the results. First, we analyze the partial data aggregation with Markovian chain; analytical result shows that, non-aggregation method suffers large energy consumption while full aggregation suffers long transmission delay. From the analysis results, we find that the proposed partial aggregation method WRP (Waterfalls Random partial aggregation) can trade off energy consumption and transmission delay. Thus, we discuss the tradeoffs among data accuracy, transmission delay and energy consumption with different criteria and parameters. The results show that we could control the significance of transmission delay, energy consumption and data accuracy by tradeoffs index (TOI). We also analyze the several applications of wireless sensor networks with different significance based on the TOI. From the observed results, we found that we could set the significance of transmission delay, energy consumption and data accuracy for different applications based on different criteria TOI. Thus, by evaluating and comparing the criteria with different data generation rate as well as aggregation factor, we get the least TOI value, which denotes the desired tradeoffs among them.

This paper discusses a buffering strategy for a delay-tolerant multimedia sensor network (DTMSN), whose typical application is video surveillance. In DTMSN, a sensor node observes events around it and stores the data in its own buffer memory. All the data is collected to the sink. Sensor nodes have restrictions on buffer memory as well as battery capacity. The entire data size is much larger than a single node's memory size. Thus, developing a strategy for buffering satisfying these restrictions is a critical issue for DTMSN. In this paper, we propose a novel buffering scheme for DTMSN called cooperative buffering (CB). In the proposed CB, the sensor node which has a large amount of data cooperates with its neighbor nodes to buffer the data in a distributed manner. CB uses mobile sinks. The cooperatively buffered data are transmitted directly to the mobile sink when it arrives. After proposing CB, this paper discusses extension for easy collection of the sink, extension for multi source nodes, and some sink mobility strategies of sink mobility. It evaluates the power consumption performance of CB via theoretical formulation and computer simulation. As a result, we show from the results that the proposed CB can handle multimedia data while operating at low-power.

In this paper, a novel medium access control (NIAC) protocol with transmission power and transmission rate control in multi-rate ad hoc networks is proposed to realize high energy efficient data transmission. In the proposed protocol, each node prepares a table that includes energy efficiency in all combinations of transmission power and rate. By exchanging of control frames and looking up the transmission power and rate table, direct and relay transmission sequences are used arbitrarily. When relay transmission by intermediate node between sender and receiver is more effective in terms of power consumption, relay sequence is adopted instead of direct transmission. We show that the proposed protocol can realize high energy efficient data transmission via computer simulations.

Recently, several directional MAC (Medium Access Control) protocols have been proposed for wireless ad hoc networks. Directional antennas have significant potentials to improve network performance. However, these directional MAC protocols also have problems which do not exist when using omni-directional antennas. One of the problems is the directional hidden terminal problem. This problem is caused by the difference of the antenna gain between the omni-directional antenna and directional antenna. In addition, a practical antenna has side and back lobes. These minor lobes have non-negligible effects on the interference in network nodes. In this paper, we propose a directional MAC protocol called DMAC-PCDR (Directional MAC with Power Control and Directional Receiving) that mitigates the interference caused by directional hidden terminals and minor lobes. DMAC-PCDR has two features. First, the nodes rotate directionally receiving antenna beams in an idle state. Second, the proposed directional MAC protocol has three access modes and uses these modes depending on the location information. The simulation results show that DMAC-PCDR improves throughput performance. © 2008 IEEE.

In this paper, a novel medium access control (MAC) protocol with transmission power and transmission rate control in multi-rate ad hoc networks is proposed to realize high energy efficient data transmission. In the proposed protocol, each node prepares a table that includes energy efficiency in all combinations of transmission power and rate. By exchanging of control frames and looking up the transmission power and rate table, direct and relay transmission sequences are used arbitrarily. When relay transmission by intermediate node between sender and receiver is more effective in terms of power consumption, relay sequence is adopted instead of direct transmission. We show that the proposed protocol can realize high energy efficient data transmission via computer simulations. ©2008 IEEE.

Directional antennas are expected to provide significant improvements over omni-directional antennas in wireless ad hoc networks. Directional MAC protocols, however, introduce new kinds of problems arising from directivity. One major problem is deafness, caused by a lack of state information from neighbor nodes (i.e., idle or busy). This paper proposes DMAC/DA (Directional MAC with Deafness Avoidance) to overcome the deafness problem. In DMAC/DA, WTS (Wait To Send) frames are transmitted by the transmitter and the receiver after the successful exchange of directional RTS (Request To Send) and CTS (Clear To Send) to notify the on-going communication to potential transmitters that may experience deafness. Furthermore, DMAC/DA is enhanced by the next packet notification to distinguish transmitters from neighbors. We evaluate our protocol through extensive simulation study with different values of parameters such as the number of flows, data size and beamwidth. The experimental results show that DMAC/DA outperforms existing directional MAC protocols, such as DMAC (Directional MAC) and MDA (MAC protocol for Directional Antennas), in terms of throughput, RTS failure ratio, and control overhead.

Recent studies on directional Media Access Control (MAC) protocols using smart antennas for wireless ad hoc networks have shown that directional MAC protocols outperform traditional omni-directional MAC protocols. Those studies evaluate performance primarily based on a simulations, where antenna beam is assumed to be ideal, i.e., with neither side-lobes nor back-lobes. Propagation conditions are also assumed to be based on a mathematical model without realistic fading. However, for the real application of ad hoc networks those optimistic assumptions do not hold anytime. In this paper, we develop at first a testbed for directional MAC protocols which enables investigation of the performance of MAC protocols in a real environment. It incorporates ESPAR as a practical smart antenna, IEEE802.15.4/ZigBee, GPS and gyro modules to allow easy installation of different MAC protocols. To our knowledge, it is the first compact testbed with a practical smart antenna for directional MAC protocols. We implement a directional MAC protocol called SWAMP to evaluate it in a real environment. The empirical discussion based on the experimental results shows the degradation of the protocol with ideal antennas, and it shows that the protocol still achieves the SDMA effect of spatial reuse and the effect of communication range extension.

Recently, several MAC protocols using directional antennas have been proposed for ad hoc networks, which are mainly evaluated by computer simulations. This paper develops a MAC protocol testbed called TRNC/ESPAR for ad hoc networks, which enables the evaluation of directional MAC protocols as well as omni-directional protocols. At first, we investigate the requirements for the testbed. Based on them, TRNC/ESPAR is designed to consist of ESPAR as a practical smart antenna, IEEE 802.15.4 as a wireless module, GPS and gyro modules to support a location dependant MAC. After describing the detail design, we investigate the basic performance of the testbed and implement CSMA/CA. Implementing one of directional AM C protocols with 4 nodes, DMA C shows that the protocol doubles the throughput compared with CSMA/CA because of SDMA effect but if the pair is too near DMAC throughput degraded in a real environment, which could not be found without the testbed.

Recent studies on directional Media Access Control (MAC) protocols using smart antennas for wireless ad hoc networks have shown that directional MAC protocols outperform traditional omni-directional MAC protocols. Those studies evaluate performance primarily based on a simulations, where antenna beam is assumed to be ideal, i.e., with neither side-lobes nor back-lobes. Propagation conditions are also assumed to be based on a mathematical model without realistic fading. However, for the real application of ad hoc networks those optimistic assumptions do not hold anytime. In this paper, we develop at first a testbed for directional MAC protocols which enables investigation of the performance of MAC protocols in a real environment. It incorporates ESPAR as a practical smart antenna, IEEE802.15.4/ZigBee, GPS and gyro modules to allow easy installation of different MAC protocols. To our knowledge, it is the first compact testbed with a practical smart antenna for directional MAC protocols. We implement a directional MAC protocol called SWAMP to evaluate it in a real environment. The empirical discussion based on the experimental results shows the degradation of the protocol with ideal antennas, and it shows that the protocol still achieves the SDMA effect of spatial reuse and the effect of communication range extension. © 2007 IEEE.

Recently, several MAC protocols using directional antennas, typically referred to as directional MAC protocols, have been proposed for wireless ad hoc networks. However, the MAC protocols in the previous studies were evaluated using simulation with ideal antenna forms. When using practical antenna beam forms, side lobes and back lobes exist which may cause new problems. In this paper, we evaluate the performance of the directional MAC protocol in the previous studies with practical antenna beam forms. In addition, we propose a directional MAC protocol that assumes practical antenna beam forms. The proposed MAC protocol mitigates data collisions due to the effects of minor lobes by the following two schemes. First, the nodes rotate directional receiving antenna beams in an idle state. Second, nodes transmit NAV (Network Allocation Vector) request frames to avoid collisions from neighboring nodes. By controlling the transmitting power, our protocol allows nodes to communicate with nodes beyond the omni-directional transmission range. The simulation results show that the proposed directional MAC protocol improves throughput performance compared to existing directional MAC protocol when using practical antenna beam forms.

Recently, several MAC protocols using directional antennas, typically referred to as directional MAC protocols, have been proposed for wireless ad hoc networks. Although directional transmissions are expected to provide significant improvements, directional MAC protocols introduce new kinds of problems. One such problem is deafness. Deafness is caused when a transmitter repeatedly attempts to communicate with its intended receiver, but it fails because the receiver has its beam pointed towards a direction away from the transmitter. This paper proposes RI-DMAC (Receiver-Initiated Directional MAC) to address the issue of deafness in directional MAC protocols. RI-DMAC is a combination of sender-initiated and receiver-initiated operations. The sender-initiated mode is the default mode and the receiver-initiated mode is triggered when the transmitter experiences deafness. In RI-DMAC, each node maintains a polling table and polls a potential deafness node using the RTR (Ready To Receive) frame after the completion of every dialog. The experimental results show that RI-DMAC improves throughput and fairness performance compared to existing directional MAC protocols.

In this paper, in order to realize the consecutive long-term operations of sensor networks, we propose a novel sustainable sensor network routing protocol considering easy node exchangeability. In the proposed routing protocol, in order to exchange nodes easily, power consumption of nodes is biased intentionally. We focus oil a routing protocol for the sustainable sensor networks. In the proposed routing protocol, the power consumption of nodes in a specific zone becomes larger than that in other zones. Battery of Nodes in the specific zone is emptied earlier As restricting the geographical area of the node exchange, node exchangeability improves. We evaluate the proposed routing protocol by means of computer simulations to show the effetiveness of the proposed routing protocol.

In this paper, we propose a novel energy efficient route construction scheme with transmission power control in ad hoe sensor networks. The proposed scheme is very simple and can improve energy consumption performance without any information of neighbor nodes. In the proposed scheme, when a node receives a route request (RREQ), the node calculates the standby time inversely proportional to the received power of the RREQ. The node relays the RREQ with full power when the standby time expires in order to construct the least energy consumption route. After the route construction, source and intermediate nodes transmit packets with power controlled medium access control (MAC) protocol. In addition, we propose the extended version of the proposed scheme to construct energy efficient route in discrete power control environment. Simulation results show the proposed scheme can construct more energy efficient route than the conventional schemes in both continuous and discrete power control environment.

Recently, several MAC protocols using directional antennas, typically referred to as directional MAC protocols, have been proposed for wireless ad hoc networks. Although directional transmissions are expected to provide significant improvements, directional MAC protocols introduce new kinds of problems. One such problem is deafness. Deafness is caused when a transmitter repeatedly attempts to communicate with its intended receiver, but it fails because the receiver has its beam pointed towards a direction away from the transmitter. This paper proposes RI-DMAC (Receiver-Initiated Directional MAC) to address the issue of deafness in directional MAC protocols. RI-DMAC is a combination of sender- initiated and receiver-initiated operations. The sender-initiated mode is the default mode and the receiverinitiated mode is triggered when the transmitter experiences deafness. In RI-DMAC, each node maintains a polling table and polls a potential deafness node using the RTR (Ready To Receive) frame after the completion of every dialog. The experimental results show that RI-DMAC improves throughput and fairness performance compared to existing directional MAC protocols. © 2006 IEEE.

This paper proposes two schemes for wireless sensor networks with multiple sinks in order to save battery energy and to improve network lifetime performance. In these schemes, each sensor node transmits sensing data to randomly chosen sink according to the sending rates. These schemes are referred to as DispersiveCast. The first decentralized scheme called B-DOP scheme (Basic DispersiveCast Of Packet), enables each sensor node to derive locally the sending rate by the number of hops to sinks. The second one is O-DOP scheme (Optimal DispersiveCast Of Packet) that is partially centralized than B-DOP. In O-DOP, sinks send the information to nodes so as for them to calculate the optimal sending rates. DispersiveCast is effective when the generate rate of sensing data at every sensor node is geographical nonuniformity. In such a situation, batteries of nodes in the specific area deplete fast and others late, which causes partial depletion of the entire network. As a result, network lifetime can not be extended sufficiently. We evaluate the DispersiveCast schemes by simulations for several network topologies and show that DispersiveCast scheme prolongs the network lifetime compared with the conventional nearest sink scheme, especially O-DOP can achieve 1.5 times longer. © 2006 IEEE.

Smart antennas are expected to enhance scalability in ad hoc networks. This paper describes the evaluations of three directional MAC protocols, DMAC, MMAC, and SWAMP, as well as the IEEE 802.11 DCF omni-directional protocol in a multihop transmission environment. These evaluations address the problem that performance strongly depends on the route topology between the source and destination, referred to as the directional hidden terminal problem. After analyzing this problem, we propose three MAC level solutions. The MAC solutions are NAV indicators, i.e. HCTS, BRTS, and RCTS, which indicate on-going communications to a directional hidden terminal to set NAV. Based on simulated results, we show that all the proposed MAC solutions could improve the throughput performance.

Smart antennas are expected to enhance scalability in ad hoc networks. This paper at first evaluates three directional MAC protocols, DMAC, MMAC and SWAMP as well as the onmi-directional protocol IEEE 802.11 DCF in multi-hop transmission environment. The evaluations address the problem that the performance strongly depends on the topology of routes between sources and destinations, referred to as a directional hidden terminal problem. After analyzing the problem, we propose three MAC level solutions and one routing level solution. The MAC solutions are directional NAV indicators which are BRTS, RCTS and HCTS to indicate on-going communications to a directional hidden terminal to set directional NAV On the other hand, the routing level solution is orthogonal routing protocol (ORP). ORP is a DSR based on-demand routing protocol and it prevents adjacent links to be in straight lines. As computer simulated results, we show that HCTS can improve the throughput performance.

Recently, several directional MAC protocols using smart antennas or directional antennas have been proposed for wireless ad hoc networks including our proposed AMC protocol called SWAMP (Smart antennas based Wider-range Access MAC Protocol). This paper first outlines issues of directional MAC protocols and investigates different factors which reduce the probability of successful transmissions, such as location information staleness, deafness and hidden- and exposed-terminal problems arisen due to directional transmissions. In addition, this paper proposes solutions of location information staleness and exposed-terminal problems. The experimental results show that the optimization of parameters associated with location information staleness, such as the beamwidth, retry limit and lifetime of the table information improves the reliability of the transmission and the overall network performance.

Smart antennas are expected to enhance scalability in ad hoc networks. This paper at first evaluates three directional MAC protocols, DMAC, MMAC and SWAMP as well as the onmi-directional protocol IEEE 802.11 DCF in multi-hop transmission environment. The evaluations address the problem that the performance strongly depends on the topology of routes between sources and destinations, referred to as a directional hidden terminal problem. After analyzing the problem, we propose three MAC level solutions and one routing level solution. The MAC solutions are directional NAV indicators which are BRTS, RCTS and HCTS to indicate on-going communications to a directional hidden terminal to set directional NAV On the other hand, the routing level solution is orthogonal routing protocol (ORP). ORP is a DSR based on-demand routing protocol and it prevents adjacent links to be in straight lines. As computer simulated results, we show that HCTS can improve the throughput performance.

The next generation (NG) wireless system called Beyond 3G is envisioned as seamless worldwide wireless systems. Handover latency is an important metric for NG wireless system. This paper analyzes the handover latency of mobility support schemes including Mobile Ethernet. We compare various mobility support schemes from multiple viewpoints. For the quantitative evaluation, we introduce an analytical network model through a Markovian model. The sequence of location update frames in four schemes, i.e., Mobile Ethernet, a scheme of using MPLS, a scheme of using VLAN tag, and Mobile IPv6, formulates the handover latency and handover costs. The combination of the latency of each switch, router, and link defines handover latency. The feature of this analysis evaluates the latency of four schemes within the same model. Numerical result shows Mobile Ethernet achieves small handover latency. By means of analytical results about handover latency and handover costs, we consider the benefit of each scheme.

In this paper, in order to avoid disconnection of a multicast path caused by the handoff of a Mobile Host (MH), we propose a multicast protocol in Mobile Internet Protocol (IP) environment. In the proposed protocol, when MH which receives multicast packets via Mobile Multicast Gateway (MMG) from Correspondent Host (CH) hands off to other networks, MMG exchanges the multicast path to reduce disconnected time without increasing utilization of bandwidth. The simulation results show that the proposed protocol can reduce both utilization of bandwidth and disconnected time compared with the conventional protocols.

In order to realize low handoff latency without increasing overhead in wired channel, we propose a handoff scheme using positional information for Mobile IP based networks. In the proposed scheme, Foreign Agents (FA) exchange IP addresses and positional information. When a distance between FA and Mobile Host (MH) exceeds a threshold, FA copies packets and forwards them only to MH's next FA. Moreover, in order for MH to receive first advertisement (ADV) message earlier, the transmission interval of ADV message is shortened in next FA. By shortening transmission interval of ADV message, MH can receive forwarded packets earlier. In addition, when new FA receives registration request (REQ) message from MH, FA replies tentative registration (TREG) message to MH. Adding tentative registration, MH can begin receiving forwarded packets without waiting for receiving registration reply (REP) message from home agent (HA). By performance evaluation using both theoretical analysis and computer simulations, we show that the proposed scheme can realize low handoff latency without increasing overhead in both wired and wireless channel.

In order to reduce the number of Binding Updates (BU) when the number of connecting Mobile Hosts (MH) is limited for higher level Mobility Anchor Point (MAP), a scheme adopting Distributed Location Management (DLM) to Multilevel Hierarchical Mobile IPnu6 (M-HMIPnu6) is proposed. In the proposed scheme, to avoid extreme load for higher level MAP, a threshold of the number of connecting MHs is set. When a MAP receives a BU and the number of connecting MHs exceeds the threshold, the MAP forwards the BU to the next MAP candidate. In addition, to reduce the number of BUs and extend a MAP domain, DLM is adopted in M-HMIPnu6. The usage of the distance field in MAP option is modified to distinguish the route redundancy and keep transparency to HMIPnu6. Moreover, to realize load balancing when mobility deviation exists, a load balancing by average BU interval in both Access Router (AR) and MH is adopted. By classifying MHs roughly by the average BU interval in AR, relatively faster MHs select higher MAPs. By performance evaluation using computer simulations, we show that the proposed scheme transparent to HMIPnu6 can reduce the number of BUs and realize load balancing without excessive route redundancy.

In order to improve both performances of the renewing time and the number of hops, we propose an adaptive Resource reSerVation Protocol (RSVP) connection renewing scheme using the address of neighbor routers in Mobile IF. In the proposed scheme, in order to renew RSVP connection after handoff of a Mobile Node (MN), each router on RSVP connection records the IP address of the downstream router in addition to the IP address of the upstream router, and the MN sends a SEARCH message. Since the router in the existing RSVP connection renews RSVP connection by means of comparing the IP address of the upstream router, the IP address of the downstream router, and the SEARCH message, the proposed scheme can renew RSVP connection neither setting up whole RSVP connection nor adding RSVP connection. We evaluate the renewing time and the number of hops of the proposed scheme and the conventional schemes by means of computer simulations. At the result, we show that the proposed scheme can improve both performances of the renewing time and the number of hops compared with the conventional schemes.