IPv6 over Low Power Wireless Personal Area Network (6LoWPAN) connects the highly constrained sensor nodes with the internet using the IPv6 protocol. 6LoWPAN has improved the scalability of the Internet of Things (IoTs) infrastructure and allows mobile nodes to send packets over the IEEE 802.15.4 wireless network. Several mobility managements schemes have been suggested for handling the registration and handover procedures in 6LoWPAN. However, these schemes have performance constraints, such as increased transmission cost, signalling overhead, registration, and handover latency. To address these issues, we propose a novel cluster-based group mobility scheme (CGM6) for 6LoWPAN. To reduce the signalling cost in the CGM6 scheme, we propose to combine the functions of the Authentication, Authorization and Accounting (AAA) server and Local Mobility Anchor (LMA) in AMAG6 (
The Internet-of-Things (IoTs) is the new rapidly evolving infrastructure that is predicted to connect 50 billion smart devices in 2025 [
Sensors are the key components of IoT, and millions of them have been deployed worldwide for various applications such as collection and measurement of data from the network [
To support mobility management, a working group NETLMM (Network-based localized mobility management) has developed a Proxy Mobile IPv6 (PMIPv6) protocol [
The LMA in 6LoWPAN is represented using the term “LMA6.” It manages the binding information of recently attached authenticated nodes by registering them on the AAA (Authentication, Authorization and Accounting) server. The LMA6 is also responsible for controlling and managing the processing and communication of data packets. The mobile nodes
To resolve the CMM scheme’s limitations, a Distributed Mobility Management (DMM) scheme has recently been proposed by IETF [
Although DMM has resolved a few issues in CMM such as single point of failure and higher expenditure and operational cost. However, due to the handover procedure performed for every individual mobile node, it suffers from signaling overhead, leading to severe battery drainage. Therefore, an efficient and fast approach is required that can resolves the signaling overhead issue in 6LoWPAN.
In this paper, we propose a novel Cluster-based Group Mobility scheme for 6LoWPAN (CGM6). The main objective of CGM6 is to overcome the signaling overhead and ensures efficient communication among the 6LoWPAN nodes during the handover process. In this approach, we introduce a new entity called AMAG6 that combines the functions of AAA server and LMA. AMAG6 is responsible for both binding and authentication process. It manages the authentication process for the group of nodes simultaneously via a group leader. The main aim of group authentication and binding is to reduce the signaling cost. AMAG6 exchanges its information with its neighboring AMAG6 during the handover process as a cluster head to reduce the number of control messages. AMAG6 is also responsible for intra-cluster and inter-cluster communication of mobile nodes. Each sub-domain is represented as a cluster comprised of a group of mobile nodes, leaders, and AMAG6 acts as a cluster head.
We summarize our contributions in this article as follows:
In this paper, a comprehensive mobility management architecture is proposed based on DMM scheme for 6LoWPAN. The proposed protocol performs handoff management by organizing MAGs in clusters. In this regard, no additional component has been added to existing DMM scheme, and functional entities are re-arranged to achieve a better performance in terms of signaling cost. A group binding strategy is proposed for 6LoWPAN. The main objective of the binding strategy is to reduce the signaling cost via binding the group of mobile nodes. The proposed CGM6 is simulated and evaluated analytically by comparing it against the state-of-the-art mobility management schemes. Our simulation results show that CGM6 reduces the handoff latency by 32%, registration delay by 11% and transmission cost by 37%.
The remainder of this article is organized as follows: Section 2 describes the proposed CGM6 scheme, including its architecture, initial registration process and handover phase. Section 3 discusses the performance of the considered schemes in terms of the handover delay, registration delay and transmission cost. Section 4 presents numerical results. Section 5 finally concludes our research efforts.
In this section, we introduce our proposed CGM6 scheme. First, we introduce the architecture of CGM6 for 6LoWPAN. Then, registration and handover procedures are discussed in detail.
The architecture of CGM6 is shown in
In the proposed CGM6 scheme, AMAG6 is responsible for authentication and binding of a group of mobile nodes via the FFD6 (Group Leader). The AMAG6 exchanges its information with its neighboring AMAG6 instead of LMA. This helps in reducing the number of control messages leading to low signaling overhead. AMAG6 handles the mobility of mobile nodes in both intra-cluster and inter-cluster scenarios. Each sub-domain is represented as a cluster comprised of a group of mobile nodes, their leaders with one AMAG6 acting as their cluster head.
At the network access level, the AMAG6s are distributed across the CGM6 architecture. The mobile nodes register with the AMAG61 through their Group Leader, as depicted in
The registration phase of the CGM6 is depicted in
Our proposed scheme describes two scenarios for signaling communication: (i) Intra-cluster, and (ii) Inter-cluster. The handover phase is illustrated in
In the intra-cluster handoff process, the MN6 moves within the same cluster and same AMAG6. AMAG6 controls the communication process for the group of mobile nodes through their leaders, i.e., FFD61 to FFD62. When an MN6 is detached from the Group Leader FFD61 and attached to the Group Leader FFD62, following steps are carried out (
In the inter-cluster scenario, MN6 moves from one AMAG6 to other AMAG6 of another cluster. During the inter-cluster communication, the following steps are performed:
This section evaluates the proposed CGM6 scheme by comparing it with CMM and DMM mobility management schemes for 6LoWPAN. All schemes are analyzed and compared based on the registration delay, handover delay & cost analysis, which are considered key performance metrics.
Parameters | Description | Values | |
---|---|---|---|
Control packet size | 1000 bytes | ||
Data packet size | 50 bytes | ||
Bandwidth (wireless link) | 11 Mbps | ||
Delay (wireless link) | 10 ms | ||
Bandwidth | 100 Mbps | ||
Delay (wired link) | 2 ms | ||
h |
Hops count between MAG-LMA | 10 | |
h |
Hops count between MAG-MAG and AMAG-MAG | 4.47 | |
h |
Hops count between MAG-AAA | 5 | |
Average delay of queuing | 5 ms | ||
Probability of failure of wireless link | 0.5 | ||
Gateways count in network | 20 | ||
a | Binding update cost on gateways | 3 | |
b | Mobile node lookup cost at gateways | 2 | |
t | Packet transmission cost (wired link) | 2 | |
k | Packet transmission cost (wireless link) | 4 | |
Probability of inter-cluster communication | 0.5 | ||
Total active hosts per gateway | 200 | ||
Time sets for connecting mobile node and gateway | 500 ms | ||
C |
Processing cost of node C for binding a packet between MAG and LMA | 5 | |
C |
Processing cost of node C for binding a packet between MAG-MAG, AMAG-AMAG and FFD-AMAG | 2.45 | |
C |
Processing cost of node C for binding a packet between MN-MAG, AMAG-CN, MAG-CN and MN-FFD | 1 |
In
The
The Total Cost (TC) in terms of signaling cost is derived for comparing the performance of CGM6 e with the state of the art. TC is calculated by adding the Binding Update Cost (BUC) with Packet Delivery Cost (PDC).
In this section, we will present the registration latency analysis of CMM, DMM, and CGM6 in 6LoWPAN.
When mobile node is attached to MAG6, it sends a RS message to MAG6 through FFD6. The MAG6 then performs authentication and reply operations with AAA server. Then the MAG6 exchanges PBU & PBA signals with LMA6. After receiving the PBA message, the MAG6 returns an RA message to mobile node. The registration latency of CMM is represented as:
When a mobile node is attached to a gateway (MAG6/LMA6), it sends an RS message to MAG6/LMA6 through the FFD6. Then, MAG6/LMA6 performs authentication request and reply operation with the AAA server. After performing the authentication, MAG6/LMA6 responds through a RA message to the mobile node. Based on the above scenario, registration latency of DMM is represented as:
In our proposed CGM6 scheme, group communication is done through the Group Leader. During the deployment of mobile nodes across the network, each MN6 in a group must register itself with the AMAG6. The MN6, as a group member, sends a message to the Group Leader FFD6. Next, FFD6 generates a list of all attached nodes and send it to the AMAG6 through an RS message. After performing the authentication process, the AMAG6 sends an RA message to the MN6 through its FFD6. The registration latency of proposed CGM6 is expressed as:
Handover latency is defined as the transmission period when a mobile node cannot receive the packets from the previous MAG6 or when a mobile node receives the first packet from the new MAG6.
When a mobile node is attached to a new MAG6(NMAG6), it sends an RS message to the NMAG6 through the FFD6. The NMAG6 exchanges authentication request and sends reply signal to the AAA server. After then, it performs PBU and PBA operations with the LMA6. The NMAG6 sends an RA message to the MN6. On receiving the PBA message, signaling delivered to a mobile node through the NMAG6. The handover latency of CMM6 is written as:
In this scheme, a mobile node attached to a gateway NMAG6/LMA6 must send an RS message to the NMAG6/LMA6 through the FFD6. Then, NMAG6/LMA6 exchanges authentication request and reply message with the AAA server. After the authentication process, NMAG6/LMA6 performs PBU and PBA operations with PMAG6/LMA6 to establish a handover tunnel. The handover latency of DMM is given below:
In this section, we describe the exchange of signaling messages for inter-cluster and intra-cluster scenario for CGM6 scheme.
In the intra-cluster handoff process, MN6 moves in the same cluster under the same cluster head MAG6. AMAG6 controls the communication process within a group of mobile nodes through its leader (FFD61 to FFD62).
This scenario describes the mobility of a mobile node between two different clusters under the different AMAG6s. Once NAMAG6(New AMAG6) receives packets from the MN6 via the RS message. Then, NAMG6 performs authentication process with PBU and also performs PBA operations with PMAG6 for groups of nodes. Then NAMAG6 sends a RA message after establishing a tunnel to MN6 through their group leaders FFD6. The handover latency of CGM6 is written as:
The TC is calculated by adding the BUC with the PDC. Next, we evaluate TC for CMM, DMM and proposed CGM6.
For CMM, the process of binding update requires the establishment of connection between the mobile node and the MAG6 which further requires
The process of packet delivery in CMM initiates by the MN6 which sends the packet from MN6 to its LMA6 through the MAG6; which further requires
Therefore, the TC of CMM6 can be expressed as:
In the DMM scheme, LMA6 and MAG6 functions are combined and the handoff procedure is performed between two neighboring MAG6 leading to reduction in LMA processing cost. The process of binding update comprises the establishment of the connection between the MN6 and the MAG6 which requires
The packet delivery process in DMM6 is done between two neighboring MAG6 and written as:
As a result, TC of DMM6 can be written as:
The proposed CGM6 scheme describes two scenarios for mobility, namely, the intra-cluster & inter-cluster mobility, respectively. For computing the TC, we considered both scenarios using the probability value (
In this scenario, the MN6 moves from one FFD6 to another FFD6 within the same AMAG6. The AMAG6 processing cost is doubled due to performing the authentication and registration functions (
For the PDC a packet is sent from the MN6 through FFD6 (group leader) to its AMAG6 (
Thus, the intra-cluster PDC can be written as:
Accordingly, the TC of CGM6 for intra-cluster mobility can be expressed as:
In this scenario, the MN6 moves between AMAG6 that are present in different clusters. AMAG61 exchange its information with its neighboring AMAG62 during handover process as a cluster head. The AMAG61 sends a binding update to another AMAG62 through a group leader is (2
After receiving a packet from the MN6, the group leader forwards the packet to the AMAG6, which requires
The TC for intra-cluster and inter-cluster scenarios of proposed CGM6 scheme can be evaluated by using the inter-cluster probability parameter
In this section, we discuss our simulation results. For the comparison of mobility management schemes, the equations presented in Section 3 are used as a performance criterion. Next, we discuss our simulation environment, then detail analysis on the obtained results is presented. The parameters and their corresponding values are given in
Parameters | Type | Values |
---|---|---|
UDP | Traffic type | CBR (Constant bitrate) |
Packet size | 1000 bytes | |
IEEE 802.11 | MAC bandwidth | 2 Mb/s |
Base station coverage area | 20 m | |
Radio-propagation model | Two ray ground | |
Topography area | ||
Wired Link (rate/delay): | Between CN & AMAG6 | 2 ms |
Between AMAG6 & AMAG6 | 2 ms | |
Antenna model | Antenna/Omni Antenna | – |
Time | Simulation end | 100 sec |
The simulation environment used for evaluating the proposed scheme CGM6 is Network Simulator version 2 (NS2). The National Institute of Standards and Technology (NIST) package based on PMIPv6 is used with simulation platform ns-2.29 (network simulator version 29) running on Ubuntu 17.10. A patch (nist-pmip6-6lowpan-ns_2.29-ubuntu12_i386.deb) which integrates 6LoWPAN and PMIPv6 is used for the simulation. All simulations are done on an Intel machine with a 2.40 GHz Core i3-3110 and 4 GB of RAM. The AWK scripting language in NS2 is used for text processing and extraction of tr (tracing) file. NAM (Network Animator) is used for the NS2.29 simulation [
We compared the proposed mobility management scheme with the existing 6LoWPAN mobility schemes: CMM and DMM. We used registration latency, handover latency and Total cost as our performance parameters.
For instance, in CMM scheme control signals are exchanged from MAG6 to LMA6 and AAA, and in CMM scheme control signals are exchanged from MAG6 to AAA. While, in the CGM6 scheme, the authentication and binding operations are performed within the AMAG6. This avoids signaling overhead during the registration process leading to better performance.
The impact of wireless link delay on total cost is shown in
This paper proposes an efficient cluster-based group mobility scheme (CGM6) for resource constrained sensor nodes in 6LoWPAN. In CGM6, the functions of AAA server and LMA are integrated into a new entity called AMAG6. AMAG6 is responsible for binding and authentication process. It reduces the signaling cost through group authentication. Further, it reduces the number of control messages by acting as a cluster head. AMAG6 is also responsible for intra-cluster and inter-cluster communications of MN6s. The performance of CGM6 is evaluated through the extensive simulations. The simulation results show that CGM6 has reduced the handoff latency by 32%, registration delay by 11% and transmission cost by 37% compared to the state-of-the-art mobility management schemes.
In this paper, we will use the terms sensor nodes and mobile nodes interchangeably.