## 2 Related Work  
Mobility of 6 LoWPAN can give rise to new and exciting applications. One of the possible applications that exploit mobile sensor nodes is healthcare, where patients wear multiple sensors so that their important health parameters like pulse rate, heart beat etc, would be monitored while they are moving. These sensor nodes form a Wireless Body Sensor Network (WBSN) and use mesh routing in order to transmit their readings to a hub or controller, which can be a PDA or a Laptop. Several existing communication technologies have been considered as a candidate of internal and external communication of WBSN. However, most of these protocols have their own shortcomings when they are used in WBSN. For example, WLAN technology is not suitable for WBSN as the low powered WBSN devices have to increase their transmission power in order to avoid interference from other powerful devices like PDA and notebook. Similarly, some communication technologies like Ultra Wideband (UWB) need complex protocols and hardware which may not be feasible for WSBN. Authors in [10] have pointed out that 6 LoWPAN can be one of the most suitable technology for WBSN since it is based on the IEEE 802.15.4 specifications. The IEEE 802.15.4 standard implies low data rate, low power, more sleeping time and less complex protocols and hardware for the sensor nodes. Its interaction with IPv6 implies that the sensor nodes should easily be interoperable with all other IP networks, including the Internet. This means that the sensor data can be accessible anywhere from the world. In [11] the authors have proposed the design of micro mobility support for a sensor node, roaming across several Access Points (AP) of a Bluetooth sensor network. A mechanism to assign IP addresses to an AP and to a sensor node so that a MN would be identified without using the channel number were also proposed. The authors also designed a middleware to carry IP packets over Bluetooth. However, they assume that the sensor node is capable to perform single hop communication even if the MN is not that close to the AP. Moreover, the MNs are expected to incorporate a middleware layer changes in their stack in order to support their mobility. Another form of mobility is network mobility or NEMO whereby the whole network moves together and their mobility is handled by MR [8]. When the network moves into a new network, the MR acquires a Care of Address (CoA) on its egress interface and sends a LU to its Home Agent (HA). The CoA informs the HA that all of the packets destined to any address derived from MR's prefix should be forwarded to the MR's CoA. However, in this scenario, the MR is comparatively more powerful as compared to a single sensor node. Thus special protocols have to be developed in order to handle the mobility of a single mobile sensor node. The authors in [12] have proposed an interoperable architecture between NEMO and 6 LoWPAN in order to support network mobility. They have suggested an extended routing scheme for MRs to support mobility in 6 LoWPAN sensor nodes. However, the architecture does not cater for individual node's mobility. The existing localized mobility-related protocols can be broadly classified into two groups. These are host-based and network-based protocols. Host-based solutions require MN involvement at the IPlayer and software changes at the host's stack. The host-based mobility protocols like MIPv6, FMIPv6, and HMIPv6 were proposed by IETF [2]. In the network-based mobility protocols, the local IP mobility is handled without involvement of the MN and also the MN does not have to implement a new mechanism in its stack. In MIPv6, when a MN moves from one network to the other, it forms a CoA based on the prefix of the foreign link. Thereafter, the node (host) itself sends the Binding Update (BU) to it's HA. When the MN receives a link layer indication of its movement it can solicit a router advertisement.