In this article, we propose a novel routing algorithm for wireless sensor network, which achieves uniform energy depletion across all the nodes and thus leading to prolonged network lifetime. The proposed algorithm, divides the Region of Interest into virtual zones, each having some designated cluster head nodes. In the entire process, a node can either be a part of a cluster or it may remain as an independent entity. A non-cluster member transmits its data to next hop node using IRPIntelligent Routing Process (based on the trade-off between the residual energy of itself as well as its neighbor, and the required energy to transmit packets to its neighbor). If on the transmission path, some cluster member is elected as a next hop, it rejects IRP and transmits the packets to cluster head, which later forwards them to sink (adopting multihop communication among cluster heads). Routing is not solely performed using clusters, rather they aid the overall routing process, hence this protocol is named as Cluster Aided Multipath Routing (CAMP). CAMP has been compared with various sensor network routing protocols, viz., LEACH, PEGASIS, DIRECT TRANSMISSION, CEED, and CBMR. It is found that the proposed algorithm outperformed them in network lifetime, energy consumption and coverage ratio.

Introduction

A wireless sensor network (WSN) consists of tiny, low powered sensors communicating with each other possibly through multi-hop wireless links and collaborating to accomplish a common task [1]. They have naturally emerged as enabling infrastructures for cyber-physical applications that closely interact with external stimulus. Homeland security, physical infrastructures monitoring, health care, building or factory automation are just a few elucidative examples of how these emerging technologies will impact our daily life and society at large [2, 3]. Sensor nodes are small micro-electromechanical systems (MEMS) devices [4, 5], which operate on limited power supplies for pervasive computing [6] and Internet of Things [7] which globally interconnect smart devices and sensor networks. Thus, it becomes essential to keep them functional as long as possible [8]. Conventional, single shortest path routing algorithms like Bellmanford [9] are not well suited in this context as they will cause significant energy depletion of nodes constituting a single shortest path, leading to shorter network lifetime [10]. Moreover, they will cause either significant degradation in the perceived quality at the sink nodes or large queuing delays due to insufficient bandwidth [12]. Traditional routing protocols of computer networks are not apt for energy constrained wireless sensor networks. All these protocols do not consider the limited memory and energy capacity of the sensor nodes. Thus, many routing protocols [11] have been proposed and specifically tailored to minimize the energy consumption of sensor nodes. They can be broadly classified into flat and hierarchical algorithms [13]. The former approach includes DD [14], SPIN [15] etc. and latter includes LEACH [16], PEGASIS [17], TEEN [18], HEED [19] etc. In flat routing, a node generally transmits its packets to neighboring nodes within its transmission range. Whereas in hierarchical routing a node transmits its data to its nearest cluster head (CH) which in turn sends it to the sink. Both the approaches have their own advantages and drawbacks. The founding principle of flat routing is cooperative multi-hop forwarding, but in doing so, a large volume of traffic is generated [in simplistic case a packet from each node is generated and forwarded to the Base Station (BS) or sink1 ] and it results in energy depletion of many nodes. Whereas, in hierarchical routing scheme, there are some designated cluster head nodes which are responsible for data aggregation from their cluster members and finally sending the aggregated information to the sink themselves. This conserves the energy of cluster members but puts a heavy toll on CHs [20, 21]. Also, since all the sensor nodes are bound to latch themselves to some CH, they may do so by communicating out of normal radio range. This further results in poor QoS [22] and degraded performance. CAMP attempt to provide a solution to the aforementioned problems by incorporating both hierarchical and flat routing strategies. It primarily divides the ROI into equal sized zones, each having a unique CH. In CAMP, only those nodes which lie in the communication range of CHs become the part of the cluster, and adopts hierarchical routing. Remaining nodes act as independent entities, and adopts multi-hop routing for communication with BS.