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Top1. Introduction
In IoT applications, the word “smart” is included everywhere such as, smart city, smart home, smart market, smart health, etc. Because the word “smart” refers the availability smart devices used in IoT applications, which works autonomously with its basic capabilities. IoT devices works smart but they are limited by energy (due to battery sourced devices). Thus, improving reliability with better network life time is the major challenge in IoT networks. In environmental monitoring applications, sensor devices are deployed in remote area (harsh environment). In commercial applications sensor devices are kept for constant observation. When nodes drainout its power in short span of time, it is difficult to replace the battery frequently, which severely affects the consumer as well as service provider (ITU, 2005; Lee et al., 2012; Boukerche, 2008). Hence energy is considered as the important resource in low power (energy constrained) wireless networks.
1.1. IoT Challenges
IoT technology is used by various applications such as, health care industries, home automation, location accuracy, weather monitoring, etc. Figure 1 elaborates the features of IoT WFRM (IOTWF), which is the generic architectural model that describes the features of IoT. In Figure 1, first three layers are handled by edge devices (sensor devices) that collects and processes the event based data (real time data), last three layers are handled by higher end devices (server, PCs, etc.) that collects and processes query based data (non real time data), middle layer is responsible for data storage (IOTWF).
Figure 1. IoT World Form Reference Model
In Figure 1 IoT challenges are included. This says energy efficiency and reliability are the major requirement for lower layers that handles low power devices. Hence energy efficiency and reliability are considered as our major objectives in proposed network design.
1.2. Energy Limitations in IoT Network
IoT network is said as “energy constrained network or low power network” due to the usage of battery sourced device and unstable radio links in IoT network (Lee et al., 2012). Internet of things is not similar to regular Internet, the following Table 1, characterize the nature of IoT and regular Internet (Vasseur and Dunkels, 2010).
Table 1. Features of IoT and regular Internet
| Features | Internet of Things | Internet |
| Nodes used | Sensors | Main power devices |
| Links | Stable links | Unstable radio links |
| Nature of Device | Energy Limited devices | Devices are not limited by energy |
| Address | IPv6 | IPv6 |
| Routing | Routing is aware of applications | Routing is not aware of applications |
| Power Source | Limited Source (Battery) | PLC |
Table 1, elaborates the energy limited nature of IoT network. Radio links used in IoT network are lossy in nature, which gives more chance for packet loss and link disconnect may occur. To avoid heavy packet loss and quick node drain out in IoT networks, stable links should be chosen for data transmission and energy should be balanced in efficient way.