IPv6-WSN: Global Communication Mechanism for ...

IPv6-WSN: Global Communication Mechanism for Future Internet Services Dhananjay Singh

IPv6-WSN: Global Communication Mechanism for Future Internet Services Dhananjay Singh Department of Electronics Engineering, Hankuk University of Foreign Studies, 89, Wangsan-ri, Mohyeon-myeon, Cheoin-gu, Yongin-si, Gyeonggi-do, 449-791, South Korea E-mail: [email protected]

Abstract IPv6 over Wireless Sensor Networks (IPv6-WSN) approaches are getting popular in real-world to establish global connectivity between (agents) machine to machine or user to machine. This scheme has to specify a specific field as personal area networks (PAN) that would be a smart field using 6lowpan (IPv6 low power wireless personal area networks) characteristics. The 6lowpan assignments are becoming the solution of choice to improve global connectivity scheme for wireless networks. In this paper, we designed MAC Framework for agent discovery and gateway discovery schemes parallel we have proposed propose an MMSP (Micro Mobility Sensor Protocol) that takes an advantage of free movement assignment to the agent. The MMSP algorithm has used to invoke small devices, based on threshold criteria in order to improve the overall throughput for wireless sensor network over 802.15.4 networks. We presented simulation experiments in order to investigate the characteristics of multichannel communication during mobile agent in wireless sensor networks using an NS-2 simulator. However, The agent only use a single radio and perform channel switching only after specified threshold is reached. We showed that performance enhancement using our proposed algorithm provides significant improvement in terms of throughput, packet delivery ratio and delay. This technique can be considered for future use for IPv6-based wireless sensor network in 802.15.4 networks.

Keywords: 6lowpan, WSN, Mobility, Smart Networks 1. Introduction Wireless Sensor Networks (WSNs) are used over a wide range which is based on several characteristics including limited transmission bandwidth, limited computation capability of individual nodes and limited energy supply. The current WSNs paradigm also has some interesting features including IPv6 connectivity, self-organization, dynamic network topology and multi-hop routing. These are important features for many real world applications to provide global connectivity, nowadays. A number of schemes, drafts, Request for Comments (RFCs), and protocols [1-3] have been proposed for IPv6 connectivity for WSN with respect to MAC, routing and Mobility. WSN cannot provide reliable and global communication with high data rate requirements because of interference, radio collision and limited bandwidth. 802.15.4 (Lowpan) needs to be connected with other Lowpans as well as with other wired networks in order to maximize the utilization of information and other resources. However, as we know, the maximum frame size of 802.15.4 is 127 octets while UDP and IPv6 have big packet size and no space for applications data. The 802.15.4 PHY layer can operate in 868MHz, 915MHz and 2.4GHz bands. In this network the sensor networks has a central controller called the PAN (personal area network) coordinator, which builds the network in its personal operating space. An IPv6-WSN based gateway assigns an IPv6 address to the WSN node. We believe that IPv6-WSN will find real applications as we see the increased discussion on the Internet of Things [10-12]. To support this vision, a large address space of IPv6 is needed, and inevitably WSNs will need to support IPv6. We also witness that IPv6 networks have been gradually deployed in some countries, and it is more convenient to connect IPv6-based WSN to IPv6 or IPv4 networks if we implement MANets based gateway in WSNs. IPv6-based WSN operating in the 802.15.4 network with respect on channel allocations, gateway discovery during the IPv6based agent movements, even though most researches [5-8] on WSN are on 802.15.4 based technology, which is developing very fast due to its low power consumption, cheap and stable

Advances in information Sciences and Service Sciences(AISS) Volume5, Number10, May 2013 doi:10.4156/AISS.vol5.issue10.97

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communication. In this network the sensor networks has a central controller called the PAN (personal area network) coordinator, which builds the network in its personal operating space. When the 802.15.4 uses same channels, their CSMA/CA functions enable them to use the different time slot. Using the different channels will cause 802.15.4 to suffer long delays while having 802.11 with a higher frequency range provides priority access of the channel in most cases. An overlap between them may adversely impact on the operation of 802.15.4. Multichannel as it relates to wireless networks is used to assign different channels to different nodes in real-time transmission. This gives rise to having data/communications on different frequency band. Channels affect the overall capacity of a wireless network. The aim of this paper is to develop a smart network for communication between agents and users for global monitoring applications. The users connects directly and checks the current status of the agent (for application- data) with the help of an existing wireless internet-based technologies such as cellular, GPS, Wifi, based services used by PDA, notebook, and cell phone.

2. IPv6-WSN Based Global Communication Mechanism In recent years, wireless sensor applications sparked, that has focused mainly on environment and industrial monitoring applications, but now different applications are emerging from all fields. The global communication has also witnessed a few new applications for wireless sensor networks, but they are a bit different as far as the issues that need to be addressed. Earlier applications focused mainly on the ways to optimize the power consumption in the network, and gave less priority to the reliability of packet transmission. However, in the global scenario the main purpose shifts from power to reliability. Thus, design of wireless applications should focus more on the reliability of packet transmission, although this does not mean that power consumption should be ignored.

Figure 1. IPv6-based wireless sensor networks for global connectivity MMSP [10] works as the back bone of the mobile IP. The idea behind the design is to modify the cellular IP in such a way as to get location information at a particular instant in time and to find the estimated velocity during handoff. To find the location of the IPV6-WSN node at a particular instant in time, directional antennae located on the Gateway are used, directed towards the highest roaming probability inside the PAN or smart networks. In this technique, the Gateway (GW) stores the location information of all IPv6-WSN nodes shown in Table 1. The MMSP knows its radius and maintains a routing table for the each of the IPv6-WSN nodes. The intermediate IPV6-WSN node also maintains a route cache as a PAN coordinator. The PAN coordinators broadcast periodic route query messages to detect available IPv6-WSN nodes in its wireless coverage or PAN. Responding to query messages, all IPv6-WSN nodes in the coverage field send route update messages. After the time elapsed during the exchange of both control packets, the MMSP calculates the distance of the IPv6-WSN from the Gateway or of the

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Gateway from other nodes. The Gateway keeps the location information of all IPv6-WSN nodes. Table 1 shows the present IPv6-WSN radial component in R1, [10]. The angle of the antenna lobe at which it receives maximum strength from a particular IPV6WSN, is taken as approximately equal to the azimuthal angle between the two, α. The values of the angles are tabulated as the current positions shown in Table 2. After the completion of consecutive control message exchanges, the MMSP again records the R2 and β for the IPV6WSN node. The Gateway maintains a routing table for the IPv6-WSN as shown in Table 2 with its position information. All position entries are taken in circular coordinates. Table 2 is updated with R2, β, using these two position values as well as the time delay between the two entities, the approximate velocity of the IPv6-WSN node is calculated and further updated in Table 3. Table 1. Present IPv6-WSN radial component in R1.

Table 2. MMSP maintains a routing table in PAN.

Table 3. MMSP maintains a route table for the Other PAN.

Whenever the MMSP receives a route update packet from the IPv6-WSN, the MMSP updates its route cache. If it receives a route update packet for the first time when a new IPv6-WSN enters its area of coverage, a new entry is made for the IPv6-WSN and the route validation time is set. If the Gateway receives a route update message from an old IPv6-WSN, it refreshes the old route; besides the route update packets, the IPv6-WSN sends a periodic page update packet to the nearest IPv6-WSN.

3. Mobility Mechanism for Global Connectivity The paper has used MAC address instead of an IPv6 address to reduce the transmission energy with shorter length of packets and the computation cost of packing and unpacking an IP header. There is a one to one mapping relationship between MAC addresses and IPv6 addresses. Hence, the MAC address is just an identifier for a sensor node. However, the packet will be discarded if any IPv6-WSN node encounters a dispatch value of 0xFFFF. As for the RERR, the destination node (gateway) cannot construct the RREP and unicasts it to the source (WSN) node. Thus, the length of the RREP packet will include the unicast MAC header and the adapt header, which can be calculated as follows: frame control field (2 bytes) + sequence number (1 byte) + destination PanID (2 bytes) + destination address (8 bytes) + source address (8 bytes) + MAC payload (adapt header (2 bytes) + length of RREQ (19 bytes) + FCS (2 bytes) = 44 bytes. The IPv6-WSN node sends a packet to the gateway using MANET routing techniques [8]. We can

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obtain the length of RREQ and RREP, 21 bytes and 19 bytes respectively. When a packet is ready for transmission and no entry for the destination exists, a RREQ will be broadcast. The used underlay protocol is 802.15.4. So, the total length of the RREQ packet will include the broadcast MAC header and the adapt header, namely 40 bytes, calculated as follows: frame control field (2 bytes) + sequence number (1 byte) + destination PanID (2 bytes) + destination address (broadcast address, 0xFFFF, 2 bytes) + source address (8 bytes) + MAC payload {adapt header (2 bytes) + length of RREQ (21bytes)} + FCS (2 bytes) = 40 bytes. It broadcasts the PAN ID (0xffff) and the destination short address (0xffff). In local repair systems, it broadcasts RREP packets with no use of destination sequence number; if it fails, then a novel protocol sends a Route Error (RERR) message to the originator of the data delivery to notify it of the broken link. For that, it uses a routing metric to evaluate route- or link-cost from originator to destination. This utilizes the Link Quality Indicator (LQI) of the IPv6 in the physical layer in routing decisions by hop distance. It utilizes the acknowledged transmission option of the MAC layer at the IPv6-WSN node for keeping connectivity of a route.

Figure 1. Mobility mechanism for global connectivity between IPv6-WSN Figure 1 has described the mobility solutions for global communication sensor networks for global connectivity between IPv6-WSN node and service provider. In this system, IPv6-WSN nodes are able to move easily within the range of PAN coordinator, which is integrated with IPv6-based wired networks. Thus, the service provider can easily get to know the current position and its application data on internet provider equipment. This integration will help realize ubiquity by allowing global to access application data across IPv6-WSN system and wired IP-based networks [8-9].The proactive, reactive and hybrid have values which define the range within the networks. When a node residing outside this range needs gateway information, it broadcasts a RREQ advertisement message broadcast to all the MANets gateway address. The nodes receiving the RREQ just rebroadcast it. Upon receipt of this RREQ, the gateway unicasts back a RREP.

4. Performance Analysis and Results In our simulation scenarios we do not assume large networks that are densely deployed; we consider 500 × 500 m2 a network for sensor surveillance system with continuous streaming data. Surveillance systems are mainly deployed for organization, smart home and hospital for remote monitoring. We will be simulating CRB traffic to be sent every 0.20 second to prevent buffer overflow and to replicate streaming data. In Figures 3-5, we analysed the performance of the number of 6 hops on the proposed MMSP (Micro Mobility Sensor Protocol) scheme by developing a complete simulation in NS 2.33 and through numerical analysis. IPv6-WSNs nodes are deployed in a 4 ×4 logical grid. The main reason of dividing the whole area into a grid is to examine the IPv6-WSNs node behavior at each step. We have used the random way point mobility model and the fluid flow mobility model. The minimum speed of IPv6-WSNs node is 1 m/s, and the maximum speed varies to 20

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m/s, 25 m/s, 30 m/s, and 35 m/s. The IPv6-WSNs node pause time is 30 sec. MMSP is used as a routing protocol. The simulation is run for 500 seconds and there are 20 simulations run. The performance metrics are analyzed for End to End Delay and Packet Delivery Ratio: Figures 3 and 4 describe the end-to-end delay and the packet delivery ratio of the packets from IPv6-WSNs node to the gateway when the speed of IPv6-WSNs node and the number of hops between them varies. After a certain number of hops, the end-to-end delay increases linearly with the increasing number of hops between the IPv6-WSNs node and the gateway. Also the end-to-end delay increases when the speed of the IPv6-WSNs node increases. This is because as the speed of the IPv6-WSNs node increases, the association of the IPv6-WSNs node with its biomedical sensor node breaks, triggering off the handoff process. Thus when the IPv6-WSNs node moves with high speed, most of the time is spent to complete the handoff process by the new IPv6-WSNs node and the old IPv6-WSNs node. Some spikes in the graph can also be observed for some early hops. There are several cases which cause these spikes. The mobility model (the random way point) because, the IPv6-WSNs node abruptly changes its position according to the mobility model, speed of IPv6-WSNs node, and pause time between movements that causes handoff and some nodes might not have routing information. MMSP broadcasts packets bring traffic in the network that not only cause collision but also introduce hidden node problem. The issues could be fixed with different network topologies, different speed, and pause time of the IPv6-WSNs node; and with the use of static routing etc. The packet delivery ratio, when the IPv6-WSNs node is far away from the gateway, i.e., 5 hops, is just about 0.4 for an IPv6-WSNs node moving with the speed of 20 m/s. As the number of hops between the gateway and the IPv6-WSNs node decreases packet delivery ratio increases. As the IPv6-WSNs node reaches closer the gateway the success ratio approaches to 1, and the end-to-end delay to 0.01 seconds. Moreover, it can be seen from Figure 3 that when the speed of the IPv6-WSNs node is 20 m/s the packet delivery ratio is better than when the speed is 25 m/s. This is because as speed increases the number of handoff increases, which can lead to a significant packet loss. Also, when the speed increases exponentially, there is a possibility that the IPv6-WSNs node will be lost in the PAN. This is because, as the new IPv6-WSNs node wakes up for the handoff process, the IPv6-WSNs node may have already crossed the new IPv6WSNs node. As shown in Figure 4 when the IPv6-WSNs node mis 5 hops away from the gateway, the packet delivery ratio at the speed of 30 m/s is almost double than that of speed of 25 m/s. It should be noted that this type of anomaly in the graph is observed due to speed of the IPv6-WSNs node that triggers routing path discovery more frequently, link congestion, and duty cycle of IPv6-WSNs node. Note that the link congestion is not caused by the IPv6-WSNs node which are relaying packets, but the IPv6-WSNs node around the IPv6-WSNs node which are participating in broadcast messages for MMSP. Also note that we have used standard MAC Protocol of 802.15.4, i.e., CSMA/CA, as underlying MAC protocol. The results of the packet delivery ratio, and the end-to-end delay could be improved significantly for MAC Protocols. The performance of our MMSP scheme in terms of end to end delay and packet delivery ratio is good when the IPv6-WSNs node is closer to the gateway. But usually it is not the case, because the IPv6-WSNs node can roam anywhere within the network. Moreover, if the network size increases the performance of our MMSP scheme decreases dramatically. Also as the speed increases the number of handoff increases, thus degrading the network lifetime as shown in Figures 3 and 4 are representing the speed of the IPv6-WSNs node, the data packets are always bridged over five hops. It is observed that, at any time instant, the IPv6-WSNs node finds itself within the vicinity of MMSP and there is a fix cost from MMSP to the other MMSP, or to the gateway. Moreover, unlike the case of our MMSP scheme, the end to end delay and packet delivery ratio do not change significantly even at different speeds of the IPv6-WSNs node. Even though, when the IPv6-WSNs node is moving in a high speed and incurring frequent handoffs, the number of hops between the MMSP and the gateway are reduced.

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End to End Delay 0.09 20 m/s 25 m/s 30 m/s 35 m/s

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Figure 3. End-to-end delays without route optimization The end to end delay for the MMSP scheme has been reduced up to twice of the delay as recorded in the MMSP scheme. Similarly the packet delivery ratio is observed to 79%, as compared to 40%, as observed in the MMSP scheme. This because the number of hops in the MMSP is less as compared to the original scheme. This decreases the delay and increases the packet delivery ratio in MMSP. The packet delivery ratio results are shown in Figure 5, as a function of the number of 4 overlapping channels. The results are similar to that of the aggregate throughput, in that, the more channels involve for transmission, the more packets are delivered. This clearly showed that contention based network perform poorly when the hops are increasing. Moreover, the additional overhead experienced during channel switching along with the mobility affect the performance. There are many factors that can influence the date delivery performance in wireless network with no exception to WSNs: the environment, network topology, traffic patterns, etc. End to End Packet Delivery Ratio 1 20 m/s 25 m/s 30 m/s 35 m/s

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Figure 4. End-to-end with route optimization

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Also, the 2.4GHz frequency band is already overcrowded with activities of other networks sharing the same unlicensed band. WSN gives a better performance at short range and with continuous streaming data long range transmission may experience many of the mentioned factors which result in poor performance and as such long range transmission not recommended for WSN. The end to end delay for the MMSP scheme has been reduced up to twice of the delay as recorded in the MMSP scheme. Similarly the packet delivery ratio is observed to 79%, as compared to 40%, as observed in the MMSP scheme. This because the number of hops in the MMSP is less as compared to the original scheme. This decreases the delay and increases the packet delivery ratio in MMSP. The packet delivery ratio results are shown in Figure 13, as a function of the number of 4 overlapping channels. The results are similar to that of the aggregate throughput, in that, the more channels involve for transmission, the more packets are delivered. This clearly showed that contention based network perform poorly when the hops are increasing. Moreover, the additional overhead experienced during channel switching along with the mobility affect the performance. There are many factors that can influence the date delivery performance in wireless network with no exception to WSNs: the environment, network topology, traffic patterns, etc.

Figure 5. QoS of end-to-end delay Also, the 2.4GHz frequency band is already overcrowded with activities of other networks sharing the same unlicensed band. WSN gives a better performance at short range and with continuous streaming data long range transmission may experience many of the mentioned factors which result in poor performance and as such long range transmission not recommended for WSN.

5. Discussion and Conclusion In this paper, we propose MMSP and super frame algorithm for the 802.15.4 protocols. This algorithm allows node to have access to multiple non-overlapping channels by accessing channels dynamically through channel switching after a set threshold has been met. During the channel based design we have discussed the need for multichannel assignment in IP-WSN. The results from the simulation results proved futile for future development in this area for 802.15.4 networks. We have presented the performance with MMSP the first multi-frequency protocol for 802.15.4 network. It has been proven that MMSP gives a better performance to operate small data rate packet sizes of up to 523 kbps. We observed that better performance is achieved when using multichannel in analyzing the impact of IP-WSN in the 802.15.4 network. Overall,

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MMSP exhibited prominent ability to utilize multichannel transmission for the future with 802.15.4 for wireless sensor surveillance system that is low-cost, reliable, easy to manage, easy to deploy and can process video data for automated real-time alerts. Researchers will be able to achieve the goal of long term, independent operation of sensor network deployments under this constraint. Also 802.11 will be able to operate within the same frequency band in the capacity of 802.15.4 which is predicted to encounter severe problems when the proposed 802.11n networks become popular. In the future, we plan to setup test-bed IP-WSN systems and evaluate the MMSP performance. We also plan to address the high switching delay experience at the sink node when receiving data from multiple sources.

6. Acknowledgement This work was supported by Hankuk University of Foreign studies, Yongin, South Korea in 2012.

7. References [1] Kushalnagar N.; Montenegro G.; Schumacher C. IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals. RFC 4919; IETF: network working group, 2007. [2] Montenegro G.; Kushalnagar N.; Hui J.; Culler D. Transmission of IPv6 Packets over IEEE 802.15.4 Networks, RFC 4944; IETF : 6lowpan working group, 2007. [3] Johnson D; Perkins C.; Arkko J. Mobility Support in IPv6, RFC 3775; IETF, 2004. [4] Singh Dhananjay. IP-Based Wireless Sensor Networks for Global Healthcare Monitoring Applications. Ph.D. Thesis. Dongseo University, Korea, 2010; p. 217. [5] Wang R.C.; Chang R.S.; Chao H.C. Internetworking between ZigBee/802.15.4 and IPv6/802.3 Network, In Proceedings of ACM SIGCOMM-workshop, Kyoto, Japan, 27–31 August 2007; pp. 362-367. [6] Winter T.; Thubert P. RPL: IPv6 Routing Protocol for Low power and Lossy Networks. IETF Internet Draft, June 2010, p. 103, (draft-ietf-roll-rpl-09). [7] Singh M.; Lee S.G.; Singh D.; Lee H.J. Impact and Performance of Mobility Models in Wireless Ad-hoc Networks. In Proceeding of 4th International Conference on Computer Sciences and Convergence Information Technology, Seoul, Korea, 14–16 November 2009; pp.139-143. [8] Singh D. Lee H.J. Design and Performance Evaluation of a Proactive Micro Mobility Protocol for Mobile Networks. In Handheld Computing for Mobile Commerce: Applications, Concepts and Technologies; IGI Global publisher: USA, 2010; Volume 1, pp. 328-342. [9] Singh D.; Tiwary U.S.; Lee H.J.; Chung W.Y. Global Healthcare Monitoring System using 6lowpan Networks. In Proceeding of 11th International Conference on Advanced Communication Technology, phoenix park, Korea, 15–18 February 2009; pp. 113-117. [10] Singh D.; Kim D. MMSP: Design a Novel Micro Mobility Sensor Protocol for Ubiquitous Communication. In Proceeding of UBICOMM2010 Conference, Florence, Italy, 25–30 October 2010; pp. 208-212. [11] Singh D.; Kim D. Performance Analysis of Gateway Discovery Techniques: IPv6 based Wireless Sensor Networks, In Proceeding of INTERNET2010 conference, Valencia, Spain, 19–24 September, 2010; pp. 142-146. [12] Hui, J.W.; Culler, D.E. Extending IP to Low-Power, Wireless Personal Area Networks. IEEE Internet Computing 2008, 12, 37-45.

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