Citation: YI, D. and YANG, H., 2016. HEER -a delay-aware and energyefficient routing protocol for wireless sensor networks. Computer Networks, 104 (July), pp. 155-173. Abstract-Minimizing energy consumption to maximize network lifetime is one of the crucial concerns in designing wireless sensor network routing protocols. Cluster-based protocols have shown promising energy-efficiency performance, where sensor nodes take turns to act as cluster heads (CHs), which carry out higher-level data routing and relaying. In such case the energy consumption is more evenly distributed for all the nodes. However, most cluster-based protocols improve energy-efficiency at the cost of transmission delay. In this paper, we propose an improved delay-aware and energy-efficient clustered protocol called Hamilton Energy-Efficient Routing Protocol (HEER). HEER forms clusters in the network initialization phase and links members in each cluster on a Hamilton Path, constructed using a greedy algorithm, for data transmission purpose. No cluster reformation is required and the members on the path will take turns to become cluster head. The design allows HEER to save on network administration energy and also balance the load comparing to traditional cluster-based protocols. The algorithms designed in HEER also means that it does not suffer long delay and does not require each node to have global location information comparing with classic chain-based protocols such as PEGASIS and its variations. We implemented the HEER protocol in MATLAB simulation and compared it with several cluster-based and chain-based protocols. We found that HEER is able to achieve an improved network lifetime over the current protocols while maintaining the average data transmission delay. In the simulation, HEER achieved 66.5% and 40.6% more rounds than LEACH and LEACH-EE, which are cluster-based protocols. When compared with chain-based protocols (PEGASIS and Intra-grid-PEGSIS), HEER managed 21.2 times and 16.7 times more rounds than PEGASIS and Intra-grid-PEGASIS respectively. In addition, HEER can eliminated 90% of transmission delay comparing to LEACH and LEACH-EE and 99% comparing with PEGASIS and Intra-grid-PEGASIS. ). consumption. In most cases SNs are battery powered and are randomly deployed in the Field of Interest (FoI) in large numbers. It is therefore difficult to receive recharge or replacement batteries frequently, if possible at all [1] . As a result, performance of WSNs is often constrained by energy, of which the consumption efficiency is one of the most important concerns for designing WSNs [2] . Wireless communication is one of the major power consuming activities on SNs and its usage is controlled mainly by the routing protocol in action. An appropriate protocol design is therefore crucial for minimizing the energy consumption. There are three main types of routing protocols in WSNs, namely flat, hierarchical and location based protocols. In Flat routing protocol, all nodes communicate in a peer-to-peer manner without any hierarchy in the structure. The advantage is having a simple, expandable and low maintenance structure. However, it lacks local and central management of communication resource and usually suffers from long and varied delay. Location-based routing protocols, on the other hand, take in consideration of the location of SNs. Relative coordinates of neighbouring nodes can be extracted from the RF communication between them or, in some cases, by incorporating on-board GPS [3]. However, location tracking devices are huge energy consumers and their performance drops in harsh environment such as coal mines, undersea and are therefore strictly limited by workspace. In hierarchical routing protocol, SNs form local structure called clusters, which consist of a cluster head (CH) and several non-cluster heads (non-CHs). CH and non-CHs in a cluster are called Cluster Members (CMs). Non-CHs transfer data through its CH, which manages the non-CHs in its cluster by allocating transmission slots for each of them. All the CHs then form the communication backbone of the network at a higher hierarchical level. Comparing with flat and local-based routing protocols, hierarchical protocol has better energy consumption efficiency and would be what we focus on in this paper. In hierarchical protocol, CHs undertake various tasks such as node association, authentication, data aggregation, data fusion and task assignments [4] . It is therefore understandable that CHs would usually have much higher energy consumption compared to non-CHs. To prevent CHs from early dying and increase network lifetime the energy consumption within the network needs to be balanced by distributing the high load of CHs among all nodes. In this paper we propose a load distribution mechanism based on Hamilton path that relief
To save energy for cluster reformation, Yi and Yang propose Hamilton energy-efficient routing protocol (HEER) REF .
HEER - A delay-aware and energy-efficient routing protocol for wireless sensor networks
Comput. Networks
Comput. Networks
Computer Science